diff --git a/Tests/Recurly/Account_Test.php b/Tests/Recurly/Account_Test.php
index d14edc47..d8f30e23 100644
--- a/Tests/Recurly/Account_Test.php
+++ b/Tests/Recurly/Account_Test.php
@@ -33,6 +33,7 @@ public function testGetAccount() {
     $this->assertEquals($account->cc_emails, 'cheryl.hines@example.com,richard.lewis@example.com');
     $this->assertEquals($account->has_paused_subscription, false);
     $this->assertEquals($account->preferred_locale, 'en-US');
+    $this->assertEquals($account->dunning_campaign_id, '1234abcd');
 
     $this->assertInstanceOf('Recurly_CustomFieldList', $account->custom_fields);
     $this->assertCount(2, $account->custom_fields);
@@ -103,6 +104,7 @@ public function testXml() {
     $account->exemption_certificate = 'Some Certificate';
     $account->entity_use_code = 'I';
     $account->preferred_locale = 'en-US';
+    $account->dunning_campaign_id = '1234abcd';
 
     $account_acquisition = new Recurly_AccountAcquisition();
     $account_acquisition->cost_in_cents = 599;
@@ -145,7 +147,7 @@ public function testXml() {
     $account->custom_fields[] = new Recurly_CustomField("serial_number", "4567-8900-1234");
 
     $this->assertEquals(
-      "<?xml version=\"1.0\"?>\n<account><account_code>act123</account_code><first_name>Verena</first_name><address><address1>123 Main St.</address1></address><tax_exempt>false</tax_exempt><entity_use_code>I</entity_use_code><shipping_addresses><shipping_address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Work</nickname><first_name>Verena</first_name><last_name>Example</last_name><company>Recurly Inc.</company></shipping_address><shipping_address><address1>123 Dolores St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Home</nickname><first_name>Verena</first_name><last_name>Example</last_name></shipping_address></shipping_addresses><preferred_locale>en-US</preferred_locale><custom_fields><custom_field><name>serial_number</name><value>4567-8900-1234</value></custom_field></custom_fields><account_acquisition><cost_in_cents>599</cost_in_cents><currency>USD</currency><channel>marketing_content</channel><subchannel>pickle sticks blog post</subchannel><campaign>mailchimp67a904de95.0914d8f4b4</campaign></account_acquisition><exemption_certificate>Some Certificate</exemption_certificate></account>\n",
+      "<?xml version=\"1.0\"?>\n<account><account_code>act123</account_code><first_name>Verena</first_name><address><address1>123 Main St.</address1></address><tax_exempt>false</tax_exempt><entity_use_code>I</entity_use_code><shipping_addresses><shipping_address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Work</nickname><first_name>Verena</first_name><last_name>Example</last_name><company>Recurly Inc.</company></shipping_address><shipping_address><address1>123 Dolores St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Home</nickname><first_name>Verena</first_name><last_name>Example</last_name></shipping_address></shipping_addresses><preferred_locale>en-US</preferred_locale><custom_fields><custom_field><name>serial_number</name><value>4567-8900-1234</value></custom_field></custom_fields><account_acquisition><cost_in_cents>599</cost_in_cents><currency>USD</currency><channel>marketing_content</channel><subchannel>pickle sticks blog post</subchannel><campaign>mailchimp67a904de95.0914d8f4b4</campaign></account_acquisition><exemption_certificate>Some Certificate</exemption_certificate><dunning_campaign_id>1234abcd</dunning_campaign_id></account>\n",
       $account->xml()
     );
   }
diff --git a/Tests/Recurly/DunningCampaign_List_Test.php b/Tests/Recurly/DunningCampaign_List_Test.php
new file mode 100644
index 00000000..14eac02d
--- /dev/null
+++ b/Tests/Recurly/DunningCampaign_List_Test.php
@@ -0,0 +1,16 @@
+<?php
+
+class RecurlyDunningCampaignListTest extends Recurly_TestCase
+{
+  function defaultResponses() {
+    return array(
+      array('GET', '/dunning_campaigns', 'dunning_campaigns/index-200.xml')
+    );
+  }
+
+  public function testLoad() {
+    $dunning_campaigns = Recurly_DunningCampaignList::get(null, $this->client);
+
+    $this->assertInstanceOf('Recurly_DunningCampaignList', $dunning_campaigns);
+  }
+}
diff --git a/Tests/Recurly/DunningCampaign_Test.php b/Tests/Recurly/DunningCampaign_Test.php
new file mode 100644
index 00000000..9b1bfb01
--- /dev/null
+++ b/Tests/Recurly/DunningCampaign_Test.php
@@ -0,0 +1,49 @@
+<?php
+
+class Recurly_DunningCampaignTest extends Recurly_TestCase
+{
+  function defaultResponses() {
+    return array(
+      array('GET', '/dunning_campaigns/1234abcd', 'dunning_campaigns/show-200.xml'),
+    );
+  }
+
+  public function testGetSingleDunningCampaign() {
+    $dunning_campaign = Recurly_DunningCampaign::get('1234abcd', $this->client);
+
+    $this->assertInstanceOf('Recurly_DunningCampaign', $dunning_campaign);
+    $this->assertEquals(3, $dunning_campaign->dunning_cycles[0]->intervals[0]->days);
+  }
+
+  public function testBulkUpdateSuccess() {
+    $this->client->addResponse('PUT', '/dunning_campaigns/1234abcd/bulk_update', 'dunning_campaigns/update-204.xml');
+
+    $dunning_campaign = Recurly_DunningCampaign::get('1234abcd', $this->client);
+
+    $plan_1 = new Recurly_Plan();
+    $plan_1->plan_code = 'platinum';
+    $plan_1->name = 'Platinum & Gold Plan';
+    $plan_1->unit_amount_in_cents->addCurrency('USD', 1500);
+    $plan_1->unit_amount_in_cents->addCurrency('EUR', 1200);
+    $plan_1->setup_fee_in_cents->addCurrency('EUR', 500);
+    $plan_1->trial_requires_billing_info = false;
+    $plan_1->total_billing_cycles = 6;
+    $plan_1->auto_renew = false;
+
+    $bulk_update_response = $dunning_campaign->bulkUpdate([$plan_1->plan_code]);
+
+    $this->assertNull($bulk_update_response);
+  }
+
+  public function testBulkUpdateFailure() {
+    $this->client->addResponse('PUT', '/dunning_campaigns/1234abcd/bulk_update', 'dunning_campaigns/update-404.xml');
+
+    $dunning_campaign = Recurly_DunningCampaign::get('1234abcd', $this->client);
+
+    try {
+      $bulk_update_response = $dunning_campaign->bulkUpdate(['foo']);
+    } catch (Exception $e) {
+      $this->assertInstanceOf('Recurly_NotFoundError', $e);
+    }
+  }
+}
diff --git a/Tests/Recurly/Invoice_Test.php b/Tests/Recurly/Invoice_Test.php
index cdd8e2e7..ece4429e 100644
--- a/Tests/Recurly/Invoice_Test.php
+++ b/Tests/Recurly/Invoice_Test.php
@@ -29,6 +29,7 @@ public function testGetInvoice() {
     $this->assertEquals($invoice->customer_notes, 'Some Customer Notes');
     $this->assertEquals($invoice->vat_reverse_charge_notes, 'Some VAT Notes');
     $this->assertEquals($invoice->invoice_number_prefix, '');
+    $this->assertEquals($invoice->dunning_campaign_id, '1234abcd');
     $this->assertEquals($invoice->invoiceNumberWithPrefix(), '1001');
   }
 
diff --git a/Tests/Recurly/Plan_Test.php b/Tests/Recurly/Plan_Test.php
index 586ad073..3614b48a 100644
--- a/Tests/Recurly/Plan_Test.php
+++ b/Tests/Recurly/Plan_Test.php
@@ -42,6 +42,7 @@ public function testGetPlan() {
     $this->assertEquals(500, $plan->setup_fee_in_cents['USD']->amount_in_cents);
     $this->assertEquals(400, $plan->setup_fee_in_cents['EUR']->amount_in_cents);
     $this->assertTrue($plan->tax_exempt);
+    $this->assertEquals('1234abcd', $plan->dunning_campaign_id);
   }
 
   public function testDeletePlan() {
@@ -60,9 +61,10 @@ public function testCreateXml() {
     $plan->trial_requires_billing_info = false;
     $plan->total_billing_cycles = 6;
     $plan->auto_renew = false;
+    $plan->dunning_campaign_id = '1234abcd';
 
     $this->assertEquals(
-      "<?xml version=\"1.0\"?>\n<plan><plan_code>platinum</plan_code><name>Platinum &amp; Gold Plan</name><unit_amount_in_cents><USD>1500</USD><EUR>1200</EUR></unit_amount_in_cents><setup_fee_in_cents><EUR>500</EUR></setup_fee_in_cents><total_billing_cycles>6</total_billing_cycles><trial_requires_billing_info>false</trial_requires_billing_info><auto_renew>false</auto_renew></plan>\n",
+      "<?xml version=\"1.0\"?>\n<plan><plan_code>platinum</plan_code><name>Platinum &amp; Gold Plan</name><unit_amount_in_cents><USD>1500</USD><EUR>1200</EUR></unit_amount_in_cents><setup_fee_in_cents><EUR>500</EUR></setup_fee_in_cents><total_billing_cycles>6</total_billing_cycles><trial_requires_billing_info>false</trial_requires_billing_info><auto_renew>false</auto_renew><dunning_campaign_id>1234abcd</dunning_campaign_id></plan>\n",
       $plan->xml()
     );
   }
@@ -78,9 +80,10 @@ public function testUpdateXml() {
     $plan->tax_exempt = false;
     $plan->trial_requires_billing_info = false;
     $plan->tax_code = 'fake-tax-code';
+    $plan->dunning_campaign_id = '1234abcd';
 
     $this->assertEquals(
-      "<?xml version=\"1.0\"?>\n<plan><plan_code>platinum</plan_code><name>Platinum Plan</name><unit_amount_in_cents><USD>1500</USD><EUR>1200</EUR></unit_amount_in_cents><setup_fee_in_cents><USD>500</USD><EUR>500</EUR></setup_fee_in_cents><total_billing_cycles nil=\"nil\"></total_billing_cycles><tax_exempt>false</tax_exempt><tax_code>fake-tax-code</tax_code><trial_requires_billing_info>false</trial_requires_billing_info></plan>\n",
+      "<?xml version=\"1.0\"?>\n<plan><plan_code>platinum</plan_code><name>Platinum Plan</name><unit_amount_in_cents><USD>1500</USD><EUR>1200</EUR></unit_amount_in_cents><setup_fee_in_cents><USD>500</USD><EUR>500</EUR></setup_fee_in_cents><total_billing_cycles nil=\"nil\"></total_billing_cycles><tax_exempt>false</tax_exempt><tax_code>fake-tax-code</tax_code><trial_requires_billing_info>false</trial_requires_billing_info><dunning_campaign_id>1234abcd</dunning_campaign_id></plan>\n",
       $plan->xml()
     );
   }
diff --git a/Tests/Recurly/Purchase_Test.php b/Tests/Recurly/Purchase_Test.php
index 3399d1d7..870b22f3 100644
--- a/Tests/Recurly/Purchase_Test.php
+++ b/Tests/Recurly/Purchase_Test.php
@@ -34,6 +34,7 @@ public function mockPurchase() {
     $purchase->account->address->country = "US";
     $purchase->account->billing_info = new Recurly_BillingInfo();
     $purchase->account->billing_info->token_id = '7z6furn4jvb9';
+    $purchase->account->dunning_campaign_id = '1234abcd';
 
     $shipping_address = new Recurly_ShippingAddress();
     $shipping_address->first_name = 'Dolores';
@@ -62,7 +63,7 @@ public function testXml() {
     $purchase = $this->mockPurchase();
 
     $this->assertEquals(
-      "<?xml version=\"1.0\"?>\n<purchase><account><account_code>aba9209a-aa61-4790-8e61-0a2692435fee</account_code><billing_info><token_id>7z6furn4jvb9</token_id></billing_info><address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone></address></account><adjustments><adjustment><currency>USD</currency><unit_amount_in_cents>1000</unit_amount_in_cents><quantity>1</quantity><revenue_schedule_type>at_invoice</revenue_schedule_type><product_code>abcd123</product_code></adjustment></adjustments><collection_method>automatic</collection_method><currency>USD</currency><customer_notes>Customer Notes</customer_notes><terms_and_conditions>Terms and Conditions</terms_and_conditions><vat_reverse_charge_notes>VAT Reverse Charge Notes</vat_reverse_charge_notes><shipping_address><address1>400 Dolores St</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><nickname>Home</nickname><first_name>Dolores</first_name><last_name>Du Monde</last_name></shipping_address><gateway_code>aBcD1234</gateway_code><transaction_type>moto</transaction_type></purchase>\n",
+      "<?xml version=\"1.0\"?>\n<purchase><account><account_code>aba9209a-aa61-4790-8e61-0a2692435fee</account_code><billing_info><token_id>7z6furn4jvb9</token_id></billing_info><address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone></address><dunning_campaign_id>1234abcd</dunning_campaign_id></account><adjustments><adjustment><currency>USD</currency><unit_amount_in_cents>1000</unit_amount_in_cents><quantity>1</quantity><revenue_schedule_type>at_invoice</revenue_schedule_type><product_code>abcd123</product_code></adjustment></adjustments><collection_method>automatic</collection_method><currency>USD</currency><customer_notes>Customer Notes</customer_notes><terms_and_conditions>Terms and Conditions</terms_and_conditions><vat_reverse_charge_notes>VAT Reverse Charge Notes</vat_reverse_charge_notes><shipping_address><address1>400 Dolores St</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><nickname>Home</nickname><first_name>Dolores</first_name><last_name>Du Monde</last_name></shipping_address><gateway_code>aBcD1234</gateway_code><transaction_type>moto</transaction_type></purchase>\n",
       $purchase->xml()
     );
   }
@@ -153,4 +154,3 @@ public function testTransactionError() {
     }
   }
 }
-
diff --git a/Tests/Recurly/Subscription_Test.php b/Tests/Recurly/Subscription_Test.php
index d76021fb..c0cddb8b 100644
--- a/Tests/Recurly/Subscription_Test.php
+++ b/Tests/Recurly/Subscription_Test.php
@@ -83,6 +83,7 @@ public function testCreateSubscriptionXml() {
     $account->last_name = 'Example';
     $account->email = 'verena@example.com';
     $account->accept_language = 'en-US';
+    $account->dunning_campaign_id = '1234abcd';
 
     $billing_info = new Recurly_BillingInfo();
     $billing_info->first_name = 'Verena';
@@ -116,7 +117,7 @@ public function testCreateSubscriptionXml() {
     $subscription->renewal_billing_cycles = 1;
 
     $this->assertEquals(
-      "<?xml version=\"1.0\"?>\n<subscription><account><account_code>account_code</account_code><username>username</username><first_name>Verena</first_name><last_name>Example</last_name><email>verena@example.com</email><accept_language>en-US</accept_language><billing_info><first_name>Verena</first_name><last_name>Example</last_name><ip_address>192.168.0.1</ip_address><number>4111-1111-1111-1111</number><month>11</month><year>2015</year><verification_value>123</verification_value></billing_info></account><plan_code>gold</plan_code><quantity>1</quantity><currency>USD</currency><subscription_add_ons></subscription_add_ons><bulk>true</bulk><terms_and_conditions>Some Terms and Conditions</terms_and_conditions><customer_notes>Some Customer Notes</customer_notes><shipping_address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Work</nickname><first_name>Verena</first_name><last_name>Example</last_name><company>Recurly Inc.</company></shipping_address><custom_fields><custom_field><name>serial_number</name><value>4567-8900-1234</value></custom_field></custom_fields><auto_renew>false</auto_renew><renewal_billing_cycles>1</renewal_billing_cycles></subscription>\n",
+      "<?xml version=\"1.0\"?>\n<subscription><account><account_code>account_code</account_code><username>username</username><first_name>Verena</first_name><last_name>Example</last_name><email>verena@example.com</email><accept_language>en-US</accept_language><billing_info><first_name>Verena</first_name><last_name>Example</last_name><ip_address>192.168.0.1</ip_address><number>4111-1111-1111-1111</number><month>11</month><year>2015</year><verification_value>123</verification_value></billing_info><dunning_campaign_id>1234abcd</dunning_campaign_id></account><plan_code>gold</plan_code><quantity>1</quantity><currency>USD</currency><subscription_add_ons></subscription_add_ons><bulk>true</bulk><terms_and_conditions>Some Terms and Conditions</terms_and_conditions><customer_notes>Some Customer Notes</customer_notes><shipping_address><address1>123 Main St.</address1><city>San Francisco</city><state>CA</state><zip>94110</zip><country>US</country><phone>555-555-5555</phone><email>verena@example.com</email><nickname>Work</nickname><first_name>Verena</first_name><last_name>Example</last_name><company>Recurly Inc.</company></shipping_address><custom_fields><custom_field><name>serial_number</name><value>4567-8900-1234</value></custom_field></custom_fields><auto_renew>false</auto_renew><renewal_billing_cycles>1</renewal_billing_cycles></subscription>\n",
       $subscription->xml()
     );
   }
@@ -332,7 +333,7 @@ public function testPostponeSubscription() {
     $subscription = Recurly_Subscription::get('012345678901234567890123456789ab', $this->client);
 
     $subscription->postpone(date('c', strtotime('2019-12-31Z')));
-    
+
     $this->assertEquals(new DateTime('2019-12-31Z'), $subscription->current_period_ends_at);
   }
 
@@ -355,10 +356,10 @@ public function testConvertTrialWith3DSToken() {
   public function testConvertTrialWithout3DSToken() {
     $this->client->addResponse('GET', '/subscriptions/012345678901234567890123456789ab', 'subscriptions/show-200-trial.xml');
     $this->client->addResponse('PUT', 'https://api.recurly.com/v2/subscriptions/012345678901234567890123456789ab/convert_trial', 'subscriptions/convert-trial-200.xml');
-    $subscription = Recurly_Subscription::get('012345678901234567890123456789ab', $this->client);    
+    $subscription = Recurly_Subscription::get('012345678901234567890123456789ab', $this->client);
     $subscription->convertTrial();
     $this->assertEquals($subscription->trial_ends_at, $subscription->current_period_started_at);
   }
 
 
-}         
+}
diff --git a/Tests/fixtures/accounts/show-200.xml b/Tests/fixtures/accounts/show-200.xml
index c1afeda4..89ca735b 100644
--- a/Tests/fixtures/accounts/show-200.xml
+++ b/Tests/fixtures/accounts/show-200.xml
@@ -50,4 +50,5 @@ Content-Type: application/xml; charset=utf-8
   <has_past_due_invoice type="boolean">false</has_past_due_invoice>
   <has_paused_subscription type="boolean">false</has_paused_subscription>
   <vat_location_valid type="boolean">true</vat_location_valid>
+  <dunning_campaign_id>1234abcd</dunning_campaign_id>
 </account>
diff --git a/Tests/fixtures/dunning_campaigns/index-200.xml b/Tests/fixtures/dunning_campaigns/index-200.xml
new file mode 100644
index 00000000..a0207293
--- /dev/null
+++ b/Tests/fixtures/dunning_campaigns/index-200.xml
@@ -0,0 +1,161 @@
+HTTP/1.1 200 OK
+Content-Type: application/xml; charset=utf-8
+
+<?xml version="1.0" encoding="UTF-8"?>
+<dunning_campaigns type="array">
+    <dunning_campaign>
+        <id>pcnqbl7k1lq8</id>
+        <code>newdefault</code>
+        <name>newdefault</name>
+        <description></description>
+        <default_campaign type="boolean">false</default_campaign>
+        <created_at type="datetime">2021-08-09T22:38:52Z</created_at>
+        <updated_at type="datetime">2021-08-09T22:38:52Z</updated_at>
+        <deleted_at nil="nil"></deleted_at>
+        <dunning_cycles type="array">
+            <dunning_cycle>
+                <type>automatic</type>
+                <applies_to_manual_trial type="boolean">false</applies_to_manual_trial>
+                <first_communication_interval type="integer">0</first_communication_interval>
+                <send_immediately_on_hard_decline type="boolean">false</send_immediately_on_hard_decline>
+                <intervals type="array">
+                    <interval>
+                        <days>0</days>
+                        <email_template>payment_declined</email_template>
+                    </interval>
+                    <interval>
+                        <days>5</days>
+                        <email_template>paymentdeclined2</email_template>
+                    </interval>
+                    <interval>
+                        <days>4</days>
+                        <email_template>paymentdeclined2</email_template>
+                    </interval>
+                    <interval>
+                        <days>1</days>
+                        <email_template>paymentdeclined2</email_template>
+                    </interval>
+                </intervals>
+                <expire_subscription type="boolean">true</expire_subscription>
+                <fail_invoice type="boolean">true</fail_invoice>
+                <total_dunning_days type="integer">10</total_dunning_days>
+                <total_recycling_days type="integer">10</total_recycling_days>
+                <version>9</version>
+                <created_at type="datetime">2021-08-31T15:56:03Z</created_at>
+                <updated_at type="datetime">2021-08-31T15:56:03Z</updated_at>
+            </dunning_cycle>
+            <dunning_cycle>
+                <type>manual</type>
+                <applies_to_manual_trial type="boolean">false</applies_to_manual_trial>
+                <first_communication_interval type="integer">0</first_communication_interval>
+                <send_immediately_on_hard_decline type="boolean">false</send_immediately_on_hard_decline>
+                <intervals type="array">
+                    <interval>
+                        <days>0</days>
+                        <email_template>invoice_past_due</email_template>
+                    </interval>
+                    <interval>
+                        <days>3</days>
+                        <email_template>subscription_canceled_nonpayment</email_template>
+                    </interval>
+                </intervals>
+                <expire_subscription type="boolean">true</expire_subscription>
+                <fail_invoice type="boolean">true</fail_invoice>
+                <total_dunning_days type="integer">3</total_dunning_days>
+                <total_recycling_days type="integer">3</total_recycling_days>
+                <version>8</version>
+                <created_at type="datetime">2021-08-09T23:16:01Z</created_at>
+                <updated_at type="datetime">2021-08-09T23:16:01Z</updated_at>
+            </dunning_cycle>
+            <dunning_cycle>
+                <type>trial</type>
+                <applies_to_manual_trial type="boolean">true</applies_to_manual_trial>
+                <first_communication_interval type="integer">0</first_communication_interval>
+                <send_immediately_on_hard_decline type="boolean">false</send_immediately_on_hard_decline>
+                <intervals type="array">
+                    <interval>
+                        <days>0</days>
+                        <email_template>post_trial_payment_declined</email_template>
+                    </interval>
+                    <interval>
+                        <days>3</days>
+                        <email_template>post_trial_payment_declined</email_template>
+                    </interval>
+                    <interval>
+                        <days>4</days>
+                        <email_template>post_trial_payment_declined</email_template>
+                    </interval>
+                    <interval>
+                        <days>3</days>
+                        <email_template>subscription_canceled_nonpayment</email_template>
+                    </interval>
+                </intervals>
+                <expire_subscription type="boolean">true</expire_subscription>
+                <fail_invoice type="boolean">true</fail_invoice>
+                <total_dunning_days type="integer">10</total_dunning_days>
+                <total_recycling_days type="integer">10</total_recycling_days>
+                <version>1</version>
+                <created_at type="datetime">2021-08-31T15:56:03Z</created_at>
+                <updated_at type="datetime">2021-08-31T15:56:03Z</updated_at>
+            </dunning_cycle>
+        </dunning_cycles>
+    </dunning_campaign>
+    <dunning_campaign>
+        <id>pbhylb5ud0wx</id>
+        <code>notdefaultthing</code>
+        <name>notdefaultthing</name>
+        <description></description>
+        <default_campaign type="boolean">false</default_campaign>
+        <created_at type="datetime">2021-08-04T02:10:24Z</created_at>
+        <updated_at type="datetime">2021-08-04T02:10:24Z</updated_at>
+        <deleted_at nil="nil"></deleted_at>
+        <dunning_cycles type="array">
+            <dunning_cycle>
+                <type>automatic</type>
+                <applies_to_manual_trial type="boolean">false</applies_to_manual_trial>
+                <first_communication_interval type="integer">0</first_communication_interval>
+                <send_immediately_on_hard_decline type="boolean">false</send_immediately_on_hard_decline>
+                <intervals type="array">
+                    <interval>
+                        <days>0</days>
+                        <email_template>subscription_canceled_nonpayment</email_template>
+                    </interval>
+                </intervals>
+                <expire_subscription type="boolean">true</expire_subscription>
+                <fail_invoice type="boolean">true</fail_invoice>
+                <total_dunning_days type="integer">0</total_dunning_days>
+                <total_recycling_days type="integer">0</total_recycling_days>
+                <version>3</version>
+                <created_at type="datetime">2021-08-05T19:18:01Z</created_at>
+                <updated_at type="datetime">2021-08-05T19:18:01Z</updated_at>
+            </dunning_cycle>
+            <dunning_cycle>
+                <type>manual</type>
+                <applies_to_manual_trial type="boolean">false</applies_to_manual_trial>
+                <first_communication_interval type="integer">0</first_communication_interval>
+                <send_immediately_on_hard_decline type="boolean">false</send_immediately_on_hard_decline>
+                <intervals type="array">
+                    <interval>
+                        <days>0</days>
+                        <email_template>invoice_past_due</email_template>
+                    </interval>
+                    <interval>
+                        <days>7</days>
+                        <email_template>invoice_past_due</email_template>
+                    </interval>
+                    <interval>
+                        <days>3</days>
+                        <email_template>subscription_canceled_nonpayment</email_template>
+                    </interval>
+                </intervals>
+                <expire_subscription type="boolean">true</expire_subscription>
+                <fail_invoice type="boolean">true</fail_invoice>
+                <total_dunning_days type="integer">10</total_dunning_days>
+                <total_recycling_days type="integer">10</total_recycling_days>
+                <version>3</version>
+                <created_at type="datetime">2021-08-05T19:18:01Z</created_at>
+                <updated_at type="datetime">2021-08-05T19:18:01Z</updated_at>
+            </dunning_cycle>
+        </dunning_cycles>
+    </dunning_campaign>
+</dunning_campaigns>
diff --git a/Tests/fixtures/dunning_campaigns/show-200.xml b/Tests/fixtures/dunning_campaigns/show-200.xml
new file mode 100644
index 00000000..e0be9d88
--- /dev/null
+++ b/Tests/fixtures/dunning_campaigns/show-200.xml
@@ -0,0 +1,36 @@
+HTTP/1.1 200 OK
+Content-Type: application/xml; charset=utf-8
+
+<?xml version="1.0" encoding="UTF-8"?>
+<dunning_campaign>
+  <id>1234abcd</id>
+  <code>code</code>
+  <name>name</name>
+  <description nil="nil"></description>
+  <default_campaign type="boolean">true</default_campaign>
+  <created_at type="datetime">2017-02-17T15:38:53Z</created_at>
+  <updated_at type="datetime">2020-02-17T15:38:53Z</updated_at>
+  <deleted_at nil="nil"></deleted_at>
+  <dunning_cycles type="array">
+    <dunning_cycle>
+      <type>automatic</type>
+      <applies_to_manual_trial type="boolean">false</applies_to_manual_trial>
+      <first_communication_interval type="integer">3</first_communication_interval>
+      <send_immediately_on_hard_decline type="boolean">true</send_immediately_on_hard_decline>
+      <intervals type="array">
+        <interval>
+          <days>3</days>
+          <email_template>subscription_canceled_nonpayment</email_template>
+        </interval>
+      </intervals>
+      <expire_subscription type="boolean">true</expire_subscription>
+      <fail_invoice type="boolean">true</fail_invoice>
+      <total_dunning_days type="integer">0</total_dunning_days>
+      <total_recycling_days type="integer">3</total_recycling_days>
+      <version>9</version>
+      <created_at type="datetime">2021-08-05T23:06:18Z</created_at>
+      <updated_at type="datetime">2021-08-05T23:06:18Z</updated_at>
+    </dunning_cycle>
+  </dunning_cycles>
+  <a name="bulk_update" href="https://api.recurly.com/v2/dunning_campaigns/1234abcd/bulk_update" method="put"/>
+</dunning_campaign>
diff --git a/Tests/fixtures/dunning_campaigns/update-204.xml b/Tests/fixtures/dunning_campaigns/update-204.xml
new file mode 100644
index 00000000..0074ded3
--- /dev/null
+++ b/Tests/fixtures/dunning_campaigns/update-204.xml
@@ -0,0 +1,2 @@
+HTTP/1.1 204 No Content
+
diff --git a/Tests/fixtures/dunning_campaigns/update-404.xml b/Tests/fixtures/dunning_campaigns/update-404.xml
new file mode 100644
index 00000000..024b7add
--- /dev/null
+++ b/Tests/fixtures/dunning_campaigns/update-404.xml
@@ -0,0 +1,8 @@
+HTTP/1.1 404 Not Found
+Content-Type: application/xml; charset=utf-8
+
+<?xml version="1.0" encoding="UTF-8"?>
+<error>
+  <symbol>not_found</symbol>
+  <description lang="en-US">Couldn't find plans with codes ["foo"]</description>
+</error>
diff --git a/Tests/fixtures/invoices/show-200.xml b/Tests/fixtures/invoices/show-200.xml
index e5a5a7ad..8845e24c 100644
--- a/Tests/fixtures/invoices/show-200.xml
+++ b/Tests/fixtures/invoices/show-200.xml
@@ -28,6 +28,7 @@ Content-Type: application/xml; charset=utf-8
   <attempt_next_collection_at nil="nil"></attempt_next_collection_at>
   <recovery_reason nil="nil"></recovery_reason>
   <tax_types nil="nil"></tax_types>
+  <dunning_campaign_id>1234abcd</dunning_campaign_id>
   <line_items type="array">
     <adjustment href="https://api.recurly.com/v2/adjustments/012345678901234567890123456789ab" type="charge">
       <account href="https://api.recurly.com/v2/accounts/1"/>
diff --git a/Tests/fixtures/plans/show-200.xml b/Tests/fixtures/plans/show-200.xml
index 6516c731..bfe7c62c 100644
--- a/Tests/fixtures/plans/show-200.xml
+++ b/Tests/fixtures/plans/show-200.xml
@@ -33,4 +33,5 @@ Content-Type: application/xml; charset=utf-8
     <USD type="integer">500</USD>
     <EUR type="integer">400</EUR>
   </setup_fee_in_cents>
+  <dunning_campaign_id>1234abcd</dunning_campaign_id>
 </plan>
diff --git a/lib/recurly.php b/lib/recurly.php
index 5366f874..9b2bd304 100644
--- a/lib/recurly.php
+++ b/lib/recurly.php
@@ -31,6 +31,10 @@
 require_once(__DIR__ . '/recurly/credit_payment_list.php');
 require_once(__DIR__ . '/recurly/custom_field.php');
 require_once(__DIR__ . '/recurly/custom_field_list.php');
+require_once(__DIR__ . '/recurly/dunning_campaign.php');
+require_once(__DIR__ . '/recurly/dunning_campaign_list.php');
+require_once(__DIR__ . '/recurly/dunning_cycle.php');
+require_once(__DIR__ . '/recurly/dunning_interval.php');
 require_once(__DIR__ . '/recurly/unique_coupon_code_list.php');
 require_once(__DIR__ . '/recurly/export_date.php');
 require_once(__DIR__ . '/recurly/export_date_list.php');
diff --git a/lib/recurly/account.php b/lib/recurly/account.php
index 2a6c1933..649c7d38 100644
--- a/lib/recurly/account.php
+++ b/lib/recurly/account.php
@@ -35,6 +35,7 @@
  * @property DateTime $closed_at For closed accounts, the date and time it was closed.
  * @property Recurly_AccountAcquisition $account_acquisition The nested account acquisition information: cost_in_cents, currency, channel, subchannel, campaign.
  * @property string $transaction_type Indicates type of resulting transaction. accepted_values: "moto".
+ * @property string $dunning_campaign_id Unique ID to identify the dunning campaign used when dunning the invoice.
  */
 class Recurly_Account extends Recurly_Resource
 {
@@ -98,7 +99,7 @@ public function createBillingInfo($billingInfo, $client = null) {
     }
     $billingInfo -> _save(Recurly_Client::POST, $this->uri() . '/billing_infos');
   }
-  
+
   public function updateBillingInfo($billingInfo, $client = null) {
     if ($client) {
       $billingInfo -> _client = $client;
@@ -141,7 +142,7 @@ protected function getWriteableAttributes() {
       'email', 'company_name', 'accept_language', 'billing_info', 'address',
       'tax_exempt', 'entity_use_code', 'cc_emails', 'shipping_addresses',
       'preferred_locale', 'custom_fields', 'account_acquisition', 'exemption_certificate',
-      'parent_account_code', 'transaction_type'
+      'parent_account_code', 'transaction_type', 'dunning_campaign_id'
     );
   }
   protected function getRequiredAttributes() {
diff --git a/lib/recurly/base.php b/lib/recurly/base.php
index 38c27c78..736060ea 100644
--- a/lib/recurly/base.php
+++ b/lib/recurly/base.php
@@ -259,6 +259,10 @@ public function getLinks() {
     'details' => 'array',
     'discount_in_cents' => 'Recurly_CurrencyList',
     'delivery' => 'Recurly_Delivery',
+    'dunning_campaign' => 'Recurly_DunningCampaign',
+    'dunning_campaigns' => 'Recurly_DunningCampaignList',
+    'dunning_cycle' => 'Recurly_DunningCycle',
+    'dunning_cycles' => 'array',
     'error' => 'Recurly_FieldError',
     'errors' => 'Recurly_ErrorList',
     'export_date' => 'Recurly_ExportDate',
@@ -269,6 +273,8 @@ public function getLinks() {
     'gift_card' => 'Recurly_GiftCard',
     'gift_cards' => 'Recurly_GiftCardList',
     'gifter_account' => 'Recurly_Account',
+    'interval' => 'Recurly_DunningInterval',
+    'intervals' => 'array',
     'invoice' => 'Recurly_Invoice',
     'invoices' => 'Recurly_InvoiceList',
     'invoice_collection' => 'Recurly_InvoiceCollection',
diff --git a/lib/recurly/client.php b/lib/recurly/client.php
index 196b3a9b..5546910a 100644
--- a/lib/recurly/client.php
+++ b/lib/recurly/client.php
@@ -82,6 +82,7 @@ class Recurly_Client
   const PATH_TRANSACTIONS = 'transactions';
   const PATH_MEASURED_UNITS = 'measured_units';
   const PATH_USAGE = 'usage';
+  const PATH_DUNNING_CAMPAIGNS = 'dunning_campaigns';
 
   /**
    * Create a new Recurly Client
diff --git a/lib/recurly/dunning_campaign.php b/lib/recurly/dunning_campaign.php
new file mode 100644
index 00000000..39755b99
--- /dev/null
+++ b/lib/recurly/dunning_campaign.php
@@ -0,0 +1,55 @@
+<?php
+
+/**
+ * Class Recurly_DunningCampaign
+ * @property string $id The uuid of the Dunning Campaign.
+ * @property string $name The name of the Dunning Campaign.
+ * @property string $code The unique dunning campaign identifier code. Only numbers, lowercase letters, dashes, pluses, and underscores can be used.
+ * @property string $description An internal description to identify a dunning campaign.
+ * @property boolean $default True if this will be your default Dunning Campaign.
+ * @property array $dunning_cycles An array of Recurly_DunningCycle hashes.
+ * @property DateTime $created_at When the Dunning Campaign was created.
+ * @property DateTime $updated_at When the Dunning Campaign was last updated.
+ * @property DateTime $deleted_at If the Dunning Campaign was deleted, this field will show the time at which that event occurred.
+ */
+class Recurly_DunningCampaign extends Recurly_Resource
+{
+  public static function get($id, $client = null) {
+    return Recurly_Base::_get(Recurly_DunningCampaign::uriForDunningCampaign($id), $client);
+  }
+
+  public function bulkUpdate($planCodes = []) {
+    $doc = $this->createDocument();
+
+    $root = $doc->appendChild($doc->createElement($this->getNodeName()));
+    $planCodesNode = $root->appendChild($doc->createElement('plan_codes'));
+
+    foreach ($planCodes as $planCode) {
+      $planCodeNode = $planCodesNode->appendChild($doc->createElement('plan_code', $planCode));
+    }
+
+    $response = $this->_client->request(Recurly_Client::PUT, $this->uri() . '/bulk_update', $this->renderXML($doc));
+    $response->assertValidResponse();
+
+    return null;
+  }
+
+  protected static function uriForDunningCampaign($id) {
+    return self::_safeUri(Recurly_Client::PATH_DUNNING_CAMPAIGNS, $id);
+  }
+
+  protected function uri() {
+    if (!empty($this->_href))
+      return $this->getHref();
+    else
+      return Recurly_DunningCampaign::uriForDunningCampaign($this->id);
+  }
+
+  protected function getNodeName() {
+    return 'dunning_campaign';
+  }
+
+  protected function getWriteableAttributes() {
+    return array();
+  }
+}
diff --git a/lib/recurly/dunning_campaign_list.php b/lib/recurly/dunning_campaign_list.php
new file mode 100644
index 00000000..8aa4cc4f
--- /dev/null
+++ b/lib/recurly/dunning_campaign_list.php
@@ -0,0 +1,13 @@
+<?php
+
+class Recurly_DunningCampaignList extends Recurly_Pager
+{
+  public static function get($params = null, $client = null) {
+    $uri = self::_uriWithParams(Recurly_Client::PATH_DUNNING_CAMPAIGNS, $params);
+    return new self($uri, $client);
+  }
+
+  protected function getNodeName() {
+    return 'dunning_campaigns';
+  }
+}
diff --git a/lib/recurly/dunning_cycle.php b/lib/recurly/dunning_cycle.php
new file mode 100644
index 00000000..998efcc5
--- /dev/null
+++ b/lib/recurly/dunning_cycle.php
@@ -0,0 +1,27 @@
+<?php
+
+/**
+ * Class Recurly_DunningCycle
+ * @property string $type
+ * @property boolean $applies_to_manual_trial
+ * @property integer $first_communication_interval
+ * @property string $send_immediately_on_hard_decline
+ * @property array $intervals
+ * @property boolean $expire_subscription
+ * @property boolean $fail_invoice
+ * @property integer $total_dunning_days
+ * @property integer $total_recycling_days
+ * @property integer $version
+ * @property DateTime $created_at
+ * @property DateTime $updated_at
+ */
+class Recurly_DunningCycle extends Recurly_Resource
+{
+  protected function getNodeName() {
+    return 'dunning_cycle';
+  }
+
+  protected function getWriteableAttributes() {
+    return array();
+  }
+}
diff --git a/lib/recurly/dunning_interval.php b/lib/recurly/dunning_interval.php
new file mode 100644
index 00000000..e77a0115
--- /dev/null
+++ b/lib/recurly/dunning_interval.php
@@ -0,0 +1,25 @@
+<?php
+/**
+ * class Recurly_DunningInterval
+ * @property int $days
+ * @property string $email_template
+ */
+class Recurly_DunningInterval extends Recurly_Resource
+{
+  protected function getNodeName() {
+    return 'interval';
+  }
+
+  protected function getWriteableAttributes() {
+   return array();
+  }
+
+  protected function populateXmlDoc(&$doc, &$node, &$obj, $nested = false) {
+    if ($this->isEmbedded($node, 'intervals')) {
+      $intervalNode = $node->appendChild($doc->createElement($this->getNodeName()));
+      parent::populateXmlDoc($doc, $intervalNode, $obj, $nested);
+    } else {
+      parent::populateXmlDoc($doc, $node, $obj, $nested);
+    }
+  }
+}
diff --git a/lib/recurly/invoice.php b/lib/recurly/invoice.php
index 12d6d7c9..1573c82b 100644
--- a/lib/recurly/invoice.php
+++ b/lib/recurly/invoice.php
@@ -43,6 +43,7 @@
  * @property string $all_transactions A link to all transactions on the invoice. Only present if there are more than 500 transactions
  * @property int $subtotal_before_discount_in_cents The total of all adjustments on the invoice before discounts or taxes are applied.
  * @property int $credit_customer_notes Allows merchant to set customer notes on a credit invoice. Will only be rejected if type is set to "charge", otherwise will be ignored if no credit invoice is created.
+ * @property string $dunning_campaign_id Unique ID to identify the dunning campaign used when dunning the invoice.
  */
 class Recurly_Invoice extends Recurly_Resource
 {
diff --git a/lib/recurly/plan.php b/lib/recurly/plan.php
index 74a43133..5ca45ed8 100644
--- a/lib/recurly/plan.php
+++ b/lib/recurly/plan.php
@@ -33,6 +33,7 @@
  * @property boolean $trial_requires_billing_info Setting to determine if subscriptions to this plan will always require billing info or will only require it when either not in a trial or when money is due, defaults to true.
  * @property boolean $auto_renew Determines whether subscriptions to this plan should auto-renew term at the end of the current term or expire. Defaults to true.
  * @property boolean $allow_any_item_on_subscriptions Used to determine whether items can be assigned as add-ons to individual subscriptions. If `true`, items can be assigned as add-ons to individual subscription add-ons. If `false`, only plan add-ons can be used.
+ * @property string $dunning_campaign_id Unique ID to identify the dunning campaign used when dunning the invoice.
  */
 class Recurly_Plan extends Recurly_Resource
 {
@@ -99,7 +100,8 @@ protected function getWriteableAttributes() {
       'trial_interval_unit', 'unit_amount_in_cents', 'setup_fee_in_cents',
       'total_billing_cycles', 'accounting_code', 'setup_fee_accounting_code',
       'revenue_schedule_type', 'setup_fee_revenue_schedule_type',
-      'tax_exempt', 'tax_code', 'trial_requires_billing_info', 'auto_renew', 'allow_any_item_on_subscriptions'
+      'tax_exempt', 'tax_code', 'trial_requires_billing_info', 'auto_renew', 'allow_any_item_on_subscriptions',
+      'dunning_campaign_id'
     );
   }
 }