diff --git a/changelog/27742.txt b/changelog/27742.txt
new file mode 100644
index 000000000000..6f958a02a7b5
--- /dev/null
+++ b/changelog/27742.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+ui: fix issue where enabling then disabling "Tidy ACME" in PKI results in failed API call.
+```
\ No newline at end of file
diff --git a/ui/app/models/pki/tidy.js b/ui/app/models/pki/tidy.js
index 896f02b2e633..1f39d0849eab 100644
--- a/ui/app/models/pki/tidy.js
+++ b/ui/app/models/pki/tidy.js
@@ -21,6 +21,7 @@ export default class PkiTidyModel extends Model {
       'The amount of time that must pass after creation that an account with no orders is marked revoked, and the amount of time after being marked revoked or deactivated.',
     detailsLabel: 'ACME account safety buffer',
     formatTtl: true,
+    defaultValue: '720h',
   })
   acmeAccountSafetyBuffer;
 
diff --git a/ui/tests/acceptance/pki/pki-tidy-test.js b/ui/tests/acceptance/pki/pki-tidy-test.js
index 2c08efd22bc2..76b75aed7bf9 100644
--- a/ui/tests/acceptance/pki/pki-tidy-test.js
+++ b/ui/tests/acceptance/pki/pki-tidy-test.js
@@ -143,6 +143,33 @@ module('Acceptance | pki tidy', function (hooks) {
     assert.strictEqual(currentRouteName(), 'vault.cluster.secrets.backend.pki.tidy.auto.index');
   });
 
+  // test coverage for a bug where toggling acme tidy on then off caused API failure
+  test('it configures a manual tidy operation', async function (assert) {
+    await authPage.login(this.pkiAdminToken);
+    await visit(`/vault/secrets/${this.mountPath}/pki/tidy`);
+    await click(PKI_TIDY.tidyEmptyStateConfigure);
+    assert.dom(PKI_TIDY.tidyConfigureModal.configureTidyModal).exists();
+    assert.dom(PKI_TIDY.tidyConfigureModal.tidyModalAutoButton).exists();
+    assert.dom(PKI_TIDY.tidyConfigureModal.tidyModalManualButton).exists();
+    await click(PKI_TIDY.tidyConfigureModal.tidyModalManualButton);
+
+    assert.dom(PKI_TIDY_FORM.tidyFormName('manual')).exists();
+    await click(PKI_TIDY_FORM.inputByAttr('tidyCertStore'));
+
+    await click(GENERAL.ttl.toggle('Tidy ACME disabled'));
+    assert
+      .dom(GENERAL.ttl.input('Tidy ACME enabled'))
+      .hasValue('30', 'acmeAccountSafetyBuffer defaults to 30 days');
+    await click('[data-test-toggle-input="Tidy ACME enabled"]');
+
+    await click(PKI_TIDY_FORM.tidySave);
+    assert.strictEqual(
+      currentRouteName(),
+      'vault.cluster.secrets.backend.pki.tidy.index',
+      'saves successfully and redirects to index'
+    );
+  });
+
   test('it opens a tidy modal when the user clicks on the tidy toolbar action', async function (assert) {
     await authPage.login(this.pkiAdminToken);
     await visit(`/vault/secrets/${this.mountPath}/pki/tidy`);
diff --git a/ui/tests/integration/components/pki/pki-tidy-form-test.js b/ui/tests/integration/components/pki/pki-tidy-form-test.js
index f04b611a1c61..e2d801fee372 100644
--- a/ui/tests/integration/components/pki/pki-tidy-form-test.js
+++ b/ui/tests/integration/components/pki/pki-tidy-form-test.js
@@ -180,7 +180,7 @@ module('Integration | Component | pki tidy form', function (hooks) {
       assert.propEqual(
         JSON.parse(req.requestBody),
         {
-          acme_account_safety_buffer: '60s',
+          acme_account_safety_buffer: '72h',
           enabled: true,
           interval_duration: '10s',
           issuer_safety_buffer: '20s',
@@ -230,7 +230,7 @@ module('Integration | Component | pki tidy form', function (hooks) {
     assert.false(this.autoTidy.tidyAcme, 'tidyAcme is false on model');
 
     await click(PKI_TIDY_FORM.toggleInput('acmeAccountSafetyBuffer'));
-    await fillIn(PKI_TIDY_FORM.acmeAccountSafetyBuffer, 60);
+    await fillIn(PKI_TIDY_FORM.acmeAccountSafetyBuffer, 3); // units are days based on defaultValue
     assert.true(this.autoTidy.tidyAcme, 'tidyAcme toggles to true');
 
     const fillInValues = {
@@ -262,6 +262,7 @@ module('Integration | Component | pki tidy form', function (hooks) {
       assert.propEqual(
         JSON.parse(req.requestBody),
         {
+          acme_account_safety_buffer: '720h',
           enabled: false,
           tidy_acme: false,
         },
@@ -294,7 +295,7 @@ module('Integration | Component | pki tidy form', function (hooks) {
       assert.ok(true, 'Request made to perform manual tidy');
       assert.propEqual(
         JSON.parse(req.requestBody),
-        { tidy_acme: false },
+        { acme_account_safety_buffer: '720h', tidy_acme: false },
         'response contains manual tidy params'
       );
       return { id: 'pki-manual-tidy' };