diff --git a/google/cloud/iam_binding.h b/google/cloud/iam_binding.h
index bfb9efad4c29c..c1977927414cc 100644
--- a/google/cloud/iam_binding.h
+++ b/google/cloud/iam_binding.h
@@ -23,16 +23,22 @@ namespace google {
 namespace cloud {
 inline namespace GOOGLE_CLOUD_CPP_NS {
 /**
- * Represents a Binding which associates a `member` with a particular `role`
- * which can be used for Identity and Access management for Cloud Platform
- * Resources.
+ * Simplified view of roles and members for IAM.
  *
- * For more information about a Binding please refer to:
- * https://cloud.google.com/resource-manager/reference/rest/Shared.Types/Binding
+ * @deprecated this class is deprecated. Any functions that use it have also
+ *     been deprecated. The class was defined before IAM conditional bindings,
+ *     and does not support them. Nor will it be able to support future IAM
+ *     features. Please use the alternative functions.
+ *
+ * @see [Identity and Access Management](https://cloud.google.com/iam)
+ * @see [Overview of IAM Conditions][iam-conditions]
+ *
+ * [iam-conditions]: https://cloud.google.com/iam/docs/conditions-overview
  */
 class IamBinding {
  public:
-  IamBinding(std::string role, std::set<std::string> members)
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED IamBinding(std::string role,
+                                             std::set<std::string> members)
       : role_(std::move(role)), members_(std::move(members)) {}
 
   std::string const& role() const { return role_; };
diff --git a/google/cloud/iam_bindings.cc b/google/cloud/iam_bindings.cc
index 49b468826d745..5c4c91306895d 100644
--- a/google/cloud/iam_bindings.cc
+++ b/google/cloud/iam_bindings.cc
@@ -17,6 +17,8 @@
 #include <algorithm>
 #include <iostream>
 #include <iterator>
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/disable_deprecation_warnings.inc"
 
 namespace google {
 namespace cloud {
diff --git a/google/cloud/iam_bindings.h b/google/cloud/iam_bindings.h
index a8d59151d98f9..72f85895ccf2f 100644
--- a/google/cloud/iam_bindings.h
+++ b/google/cloud/iam_bindings.h
@@ -17,6 +17,8 @@
 
 #include "google/cloud/iam_binding.h"
 #include "google/cloud/version.h"
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/disable_deprecation_warnings.inc"
 #include <map>
 #include <set>
 #include <string>
@@ -27,25 +29,32 @@ namespace google {
 namespace cloud {
 inline namespace GOOGLE_CLOUD_CPP_NS {
 /**
- * Represents a container for providing users with a handful of operation to
- * users which they can use to add and remove members to Binding which is used
- * for defining IAM Policy for Cloud Platform Resources.
+ * Simplified view of multiple roles and their members for IAM.
  *
- * For more information about a Binding please refer to:
- * https://cloud.google.com/resource-manager/reference/rest/Shared.Types/Binding
+ * @deprecated this class is deprecated. Any functions that use it have also
+ *     been deprecated. The class was defined before IAM conditional bindings,
+ *     and does not support them. Nor will it be able to support future IAM
+ *     features. Please use the alternative functions.
+ *
+ * @see [Identity and Access Management](https://cloud.google.com/iam)
+ * @see [Overview of IAM Conditions][iam-conditions]
+ *
+ * [iam-conditions]: https://cloud.google.com/iam/docs/conditions-overview
  */
 class IamBindings {
  public:
   IamBindings() = default;
 
-  // NOLINTNEXTLINE(performance-unnecessary-value-param)
-  explicit IamBindings(std::vector<IamBinding> bindings) {
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED explicit IamBindings(
+      // NOLINTNEXTLINE(performance-unnecessary-value-param)
+      std::vector<IamBinding> bindings) {
     for (auto& it : bindings) {
       bindings_.insert({std::move(it.role()), std::move(it.members())});
     }
   }
 
-  IamBindings(std::string role, std::set<std::string> members) {
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED IamBindings(std::string role,
+                                              std::set<std::string> members) {
     bindings_.insert({std::move(role), std::move(members)});
   }
 
@@ -55,28 +64,37 @@ class IamBindings {
    * Returns an iterator referring to the first element in IamBindings
    * container.
    */
-  iterator begin() const { return bindings_.begin(); }
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED iterator begin() const {
+    return bindings_.begin();
+  }
 
   /**
    * Returns an iterator referring to the past-the-end element in IamBindings
    * container.
    */
-  iterator end() const { return bindings_.end(); }
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED iterator end() const {
+    return bindings_.end();
+  }
 
   /**
    * Returns whether the Bindings container is empty.
    *
    * @return bool whether the container is empty or not.
    */
-  bool empty() const { return bindings_.empty(); }
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED bool empty() const {
+    return bindings_.empty();
+  }
 
   /**
    * Return number of Bindings in container.
    *
    * @return int the size of the container.
    */
-  std::size_t size() const { return bindings_.size(); }
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED std::size_t size() const {
+    return bindings_.size();
+  }
 
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED
   std::map<std::string, std::set<std::string>> const& bindings() const {
     return bindings_;
   }
@@ -84,10 +102,13 @@ class IamBindings {
   /**
    * Finds the members for a role.
    */
-  iterator find(std::string const& role) const { return bindings_.find(role); }
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED iterator find(std::string const& role) const {
+    return bindings_.find(role);
+  }
 
   /// Returns the members for a role.
-  std::set<std::string> at(std::string const& role) const {
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED std::set<std::string> at(
+      std::string const& role) const {
     auto loc = bindings_.find(role);
     if (loc == bindings_.end()) {
       return {};
@@ -103,7 +124,8 @@ class IamBindings {
    * @param member specifies the identity requesting access for a cloud
    * platform resource.
    */
-  void AddMember(std::string const& role, std::string member);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void AddMember(std::string const& role,
+                                                 std::string member);
 
   /**
    * Adds a new key-value pair of role and members to the container if there is
@@ -112,7 +134,8 @@ class IamBindings {
    *
    * @param iam_binding binding representing a set of members and role for them.
    */
-  void AddMembers(google::cloud::IamBinding const& iam_binding);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void AddMembers(
+      google::cloud::IamBinding const& iam_binding);
 
   /**
    * Adds a new key-value pair of role and members to the container if there no
@@ -122,8 +145,8 @@ class IamBindings {
    * @param role role of the member set to be added.
    * @param members a set of member which are needed to be added.
    */
-  void AddMembers(std::string const& role,
-                  std::set<std::string> const& members);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void AddMembers(
+      std::string const& role, std::set<std::string> const& members);
 
   /**
    * Removes the given member from the given role's member set if there exists
@@ -133,7 +156,8 @@ class IamBindings {
    * @param member specifies the identity requesting access for a cloud
    * platform resource.
    */
-  void RemoveMember(std::string const& role, std::string const& member);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void RemoveMember(std::string const& role,
+                                                    std::string const& member);
 
   /**
    * Removes the given binding's member from the given binding's role's member
@@ -141,7 +165,8 @@ class IamBindings {
    *
    * @param iam_binding binding representing a set of members and role for them.
    */
-  void RemoveMembers(google::cloud::IamBinding const& iam_binding);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void RemoveMembers(
+      google::cloud::IamBinding const& iam_binding);
 
   /**
    * Removes the given members from given role's member set if there exists one
@@ -150,8 +175,8 @@ class IamBindings {
    * @param role role of the member set to be removed.
    * @param members a set of members which are needed to be removed.
    */
-  void RemoveMembers(std::string const& role,
-                     std::set<std::string> const& members);
+  GOOGLE_CLOUD_CPP_IAM_DEPRECATED void RemoveMembers(
+      std::string const& role, std::set<std::string> const& members);
 
  private:
   std::map<std::string, std::set<std::string>> bindings_;
@@ -187,4 +212,6 @@ std::ostream& operator<<(std::ostream& os, IamBindings const& rhs);
 }  // namespace cloud
 }  // namespace google
 
+#include "google/cloud/internal/diagnostics_pop.inc"
+
 #endif  // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_IAM_BINDINGS_H
diff --git a/google/cloud/iam_bindings_test.cc b/google/cloud/iam_bindings_test.cc
index 232b0190be58f..e224f1260f33c 100644
--- a/google/cloud/iam_bindings_test.cc
+++ b/google/cloud/iam_bindings_test.cc
@@ -14,6 +14,8 @@
 
 #include "google/cloud/iam_bindings.h"
 #include <gmock/gmock.h>
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/disable_deprecation_warnings.inc"
 
 namespace google {
 namespace cloud {
diff --git a/google/cloud/iam_policy.h b/google/cloud/iam_policy.h
index f2fa8ba804bef..c101ada56d651 100644
--- a/google/cloud/iam_policy.h
+++ b/google/cloud/iam_policy.h
@@ -23,16 +23,17 @@ namespace google {
 namespace cloud {
 inline namespace GOOGLE_CLOUD_CPP_NS {
 /**
- * Represent the result of a GetIamPolicy or SetIamPolicy request.
+ * A deprecated representation of IAM policies.
  *
- * This is a simple struct to hold the version, IamBindings, and ETag.
+ * @deprecated this class is deprecated. Any functions that use it have also
+ *     been deprecated. The class was defined before IAM conditional bindings,
+ *     and does not support them. Nor will it be able to support future IAM
+ *     features. Please use the alternative functions.
  *
- * @see
- * https://cloud.google.com/resource-manager/reference/rest/Shared.Types/Policy
- *     for more information about IAM policies.
+ * @see [Identity and Access Management](https://cloud.google.com/iam)
+ * @see [Overview of IAM Conditions][iam-conditions]
  *
- * @see https://tools.ietf.org/html/rfc7232#section-2.3 for more information
- *     about ETags.
+ * [iam-conditions]: https://cloud.google.com/iam/docs/conditions-overview
  */
 struct IamPolicy {
   std::int32_t version;
diff --git a/google/cloud/storage/internal/bucket_requests.cc b/google/cloud/storage/internal/bucket_requests.cc
index c42ce0773bb96..87978e9053330 100644
--- a/google/cloud/storage/internal/bucket_requests.cc
+++ b/google/cloud/storage/internal/bucket_requests.cc
@@ -273,6 +273,9 @@ Status ValidateIamBinding(nlohmann::json const& binding,
 }
 }  // namespace
 
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/disable_deprecation_warnings.inc"
+
 StatusOr<IamPolicy> ParseIamPolicyFromString(std::string const& payload) {
   auto json = nlohmann::json::parse(payload, nullptr, false);
   if (!json.is_object()) {
@@ -324,6 +327,9 @@ SetBucketIamPolicyRequest::SetBucketIamPolicyRequest(
   json_payload_ = iam.dump();
 }
 
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/diagnostics_pop.inc"
+
 std::ostream& operator<<(std::ostream& os, SetBucketIamPolicyRequest const& r) {
   os << "GetBucketIamPolicyRequest={bucket_name=" << r.bucket_name();
   r.DumpOptions(os, ", ");
diff --git a/google/cloud/storage/internal/bucket_requests_test.cc b/google/cloud/storage/internal/bucket_requests_test.cc
index 3155fddcc6ce5..c711d681bd986 100644
--- a/google/cloud/storage/internal/bucket_requests_test.cc
+++ b/google/cloud/storage/internal/bucket_requests_test.cc
@@ -23,6 +23,8 @@
 #include "google/cloud/testing_util/status_matchers.h"
 #include <gmock/gmock.h>
 #include <nlohmann/json.hpp>
+// TODO(#5929) - remove after decommission is completed
+#include "google/cloud/internal/disable_deprecation_warnings.inc"
 
 namespace google {
 namespace cloud {
diff --git a/google/cloud/version.h b/google/cloud/version.h
index 4d3d19b49c3c5..e707192f6d134 100644
--- a/google/cloud/version.h
+++ b/google/cloud/version.h
@@ -15,10 +15,18 @@
 #ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_VERSION_H
 #define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_VERSION_H
 
+#include "google/cloud/internal/attributes.h"
 #include "google/cloud/internal/port_platform.h"
 #include "google/cloud/internal/version_info.h"
 #include <string>
 
+#define GOOGLE_CLOUD_CPP_IAM_DEPRECATED                                    \
+  GOOGLE_CLOUD_CPP_DEPRECATED(                                             \
+      "this type predates IAM conditions and does not work with policies " \
+      "that include IAM conditions. The functions that use this type are " \
+      "deprecated and will be be removed on 2022-04-01 or shortly "        \
+      "after. See GitHub issue #5929 for more information.")
+
 #define GOOGLE_CLOUD_CPP_VCONCAT(Ma, Mi) v##Ma
 #define GOOGLE_CLOUD_CPP_VEVAL(Ma, Mi) GOOGLE_CLOUD_CPP_VCONCAT(Ma, Mi)
 #define GOOGLE_CLOUD_CPP_NS                              \