diff --git a/changelogs/fragments/562-rds_subnet_group-tags-and-check_mode.yaml b/changelogs/fragments/562-rds_subnet_group-tags-and-check_mode.yaml
new file mode 100644
index 00000000000..6fdaa2e6b87
--- /dev/null
+++ b/changelogs/fragments/562-rds_subnet_group-tags-and-check_mode.yaml
@@ -0,0 +1,3 @@
+minor_changes:
+- rds_subnet_group - add ``tags`` feature (https://github.com/ansible-collections/community.aws/pull/562).
+- rds_subnet_group - add ``check_mode`` (https://github.com/ansible-collections/community.aws/pull/562).
diff --git a/plugins/modules/rds_subnet_group.py b/plugins/modules/rds_subnet_group.py
index 7d789481c43..b0a9f8ae806 100644
--- a/plugins/modules/rds_subnet_group.py
+++ b/plugins/modules/rds_subnet_group.py
@@ -39,7 +39,21 @@
       - Required when I(state=present).
     type: list
     elements: str
-author: "Scott Anderson (@tastychutney)"
+  tags:
+    description:
+      - A hash/dictionary of tags to add to the new RDS subnet group or to add/remove from an existing one.
+    type: dict
+    version_added: 3.2.0
+  purge_tags:
+    description:
+       - Whether or not to remove tags assigned to the RDS subnet group if not specified in the playbook.
+       - To remove all tags set I(tags) to an empty dictionary in conjunction with this.
+    default: True
+    type: bool
+    version_added: 3.2.0
+author:
+    - "Scott Anderson (@tastychutney)"
+    - "Alina Buzachis (@alinabuzachis)"
 extends_documentation_fragment:
 - amazon.aws.aws
 - amazon.aws.ec2
@@ -56,6 +70,18 @@
       - subnet-aaaaaaaa
       - subnet-bbbbbbbb
 
+- name: Add or change a subnet group and associate tags
+  community.aws.rds_subnet_group:
+    state: present
+    name: norwegian-blue
+    description: My Fancy Ex Parrot Subnet Group
+    subnets:
+      - subnet-aaaaaaaa
+      - subnet-bbbbbbbb
+    tags:
+      tag1: Tag1
+      tag2: Tag2
+
 - name: Remove a subnet group
   community.aws.rds_subnet_group:
     state: absent
@@ -63,6 +89,11 @@
 '''
 
 RETURN = r'''
+changed:
+    description: True if listing the RDS subnet group succeeds.
+    type: bool
+    returned: always
+    sample: "false"
 subnet_group:
     description: Dictionary of DB subnet group values
     returned: I(state=present)
@@ -72,46 +103,95 @@
             description: The name of the DB subnet group (maintained for backward compatibility)
             returned: I(state=present)
             type: str
+            sample: "ansible-test-mbp-13950442"
         db_subnet_group_name:
             description: The name of the DB subnet group
             returned: I(state=present)
             type: str
+            sample: "ansible-test-mbp-13950442"
         description:
             description: The description of the DB subnet group (maintained for backward compatibility)
             returned: I(state=present)
             type: str
+            sample: "Simple description."
         db_subnet_group_description:
             description: The description of the DB subnet group
             returned: I(state=present)
             type: str
+            sample: "Simple description."
         vpc_id:
             description: The VpcId of the DB subnet group
             returned: I(state=present)
             type: str
+            sample: "vpc-0acb0ba033ff2119c"
         subnet_ids:
             description: Contains a list of Subnet IDs
             returned: I(state=present)
             type: list
+            sample:
+                "subnet-08c94870f4480797e"
         subnets:
             description: Contains a list of Subnet elements (@see https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/rds.html#RDS.Client.describe_db_subnet_groups) # noqa
             returned: I(state=present)
             type: list
+            contains:
+                subnet_availability_zone:
+                    description: Contains Availability Zone information.
+                    returned: I(state=present)
+                    type: dict
+                    version_added: 3.2.0
+                    sample:
+                        name: "eu-north-1b"
+                subnet_identifier:
+                    description: The identifier of the subnet.
+                    returned: I(state=present)
+                    type: str
+                    version_added: 3.2.0
+                    sample: "subnet-08c94870f4480797e"
+                subnet_outpost:
+                    description: This value specifies the Outpost.
+                    returned: I(state=present)
+                    type: dict
+                    version_added: 3.2.0
+                    sample: {}
+                subnet_status:
+                    description: The status of the subnet.
+                    returned: I(state=present)
+                    type: str
+                    version_added: 3.2.0
+                    sample: "Active"
         status:
             description: The status of the DB subnet group (maintained for backward compatibility)
             returned: I(state=present)
             type: str
+            sample: "Complete"
         subnet_group_status:
             description: The status of the DB subnet group
             returned: I(state=present)
             type: str
+            sample: "Complete"
         db_subnet_group_arn:
             description: The ARN of the DB subnet group
             returned: I(state=present)
             type: str
+            sample: "arn:aws:rds:eu-north-1:721066863947:subgrp:ansible-test-13950442"
+        tags:
+            description: The tags associated with the subnet group
+            returned: I(state=present)
+            type: dict
+            version_added: 3.2.0
+            sample:
+                tag1: Tag1
+                tag2: Tag2
 '''
 
 from ansible.module_utils.common.dict_transformations import camel_dict_to_snake_dict
-from ansible_collections.amazon.aws.plugins.module_utils.core import AnsibleAWSModule, is_boto3_error_code
+from ansible_collections.amazon.aws.plugins.module_utils.core import AnsibleAWSModule
+from ansible_collections.amazon.aws.plugins.module_utils.core import is_boto3_error_code
+from ansible_collections.amazon.aws.plugins.module_utils.ec2 import ansible_dict_to_boto3_tag_list
+from ansible_collections.amazon.aws.plugins.module_utils.ec2 import AWSRetry
+from ansible_collections.amazon.aws.plugins.module_utils.rds import get_tags
+from ansible_collections.amazon.aws.plugins.module_utils.rds import ensure_tags
 
 
 try:
@@ -125,7 +205,7 @@ def create_result(changed, subnet_group=None):
         return dict(
             changed=changed
         )
-    result_subnet_group = dict(camel_dict_to_snake_dict(subnet_group))
+    result_subnet_group = dict(subnet_group)
     result_subnet_group['name'] = result_subnet_group.get(
         'db_subnet_group_name')
     result_subnet_group['description'] = result_subnet_group.get(
@@ -133,15 +213,39 @@ def create_result(changed, subnet_group=None):
     result_subnet_group['status'] = result_subnet_group.get(
         'subnet_group_status')
     result_subnet_group['subnet_ids'] = create_subnet_list(
-        subnet_group.get('Subnets'))
+        subnet_group.get('subnets'))
     return dict(
         changed=changed,
         subnet_group=result_subnet_group
     )
 
 
+@AWSRetry.jittered_backoff()
+def _describe_db_subnet_groups_with_backoff(client, **kwargs):
+    paginator = client.get_paginator('describe_db_subnet_groups')
+    return paginator.paginate(**kwargs).build_full_result()
+
+
+def get_subnet_group(client, module):
+    params = dict()
+    params['DBSubnetGroupName'] = module.params.get('name').lower()
+
+    try:
+        _result = _describe_db_subnet_groups_with_backoff(client, **params)
+    except is_boto3_error_code('DBSubnetGroupNotFoundFault'):
+        return None
+    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:  # pylint: disable=duplicate-except
+        module.fail_json_aws(e, msg="Couldn't describe subnet groups.")
+
+    if _result:
+        result = camel_dict_to_snake_dict(_result['DBSubnetGroups'][0])
+        result['tags'] = get_tags(client, module, result['db_subnet_group_arn'])
+
+    return result
+
+
 def create_subnet_list(subnets):
-    '''
+    r'''
     Construct a list of subnet ids from a list of subnets dicts returned by boto3.
     Parameters:
         subnets (list): A list of subnets definitions.
@@ -151,7 +255,7 @@ def create_subnet_list(subnets):
     '''
     subnets_ids = []
     for subnet in subnets:
-        subnets_ids.append(subnet.get('SubnetIdentifier'))
+        subnets_ids.append(subnet.get('subnet_identifier'))
     return subnets_ids
 
 
@@ -161,64 +265,111 @@ def main():
         name=dict(required=True),
         description=dict(required=False),
         subnets=dict(required=False, type='list', elements='str'),
+        tags=dict(required=False, type='dict'),
+        purge_tags=dict(type='bool', default=True),
     )
     required_if = [('state', 'present', ['description', 'subnets'])]
+
     module = AnsibleAWSModule(
-        argument_spec=argument_spec, required_if=required_if)
+        argument_spec=argument_spec,
+        required_if=required_if,
+        supports_check_mode=True
+    )
+
     state = module.params.get('state')
     group_name = module.params.get('name').lower()
     group_description = module.params.get('description')
     group_subnets = module.params.get('subnets') or []
 
     try:
-        conn = module.client('rds')
+        connection = module.client('rds', retry_decorator=AWSRetry.jittered_backoff())
     except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
-        module.fail_json_aws(e, 'Failed to instantiate AWS connection')
+        module.fail_json_aws(e, 'Failed to instantiate AWS connection.')
+
     # Default.
+    changed = None
     result = create_result(False)
+    tags_update = False
+    subnet_update = False
 
-    try:
-        matching_groups = conn.describe_db_subnet_groups(
-            DBSubnetGroupName=group_name, MaxRecords=100).get('DBSubnetGroups')
-    except is_boto3_error_code('DBSubnetGroupNotFoundFault'):
-        # No existing subnet, create it if needed, else we can just exit.
-        if state == 'present':
+    if module.params.get("tags") is not None:
+        _tags = ansible_dict_to_boto3_tag_list(module.params.get("tags"))
+    else:
+        _tags = list()
+
+    matching_groups = get_subnet_group(connection, module)
+
+    if state == 'present':
+        if matching_groups:
+            # We have one or more subnets at this point.
+
+            # Check if there is any tags update
+            tags_update = ensure_tags(
+                connection,
+                module,
+                matching_groups['db_subnet_group_arn'],
+                matching_groups['tags'],
+                module.params.get("tags"),
+                module.params['purge_tags']
+            )
+
+            # Sort the subnet groups before we compare them
+            existing_subnets = create_subnet_list(matching_groups['subnets'])
+            existing_subnets.sort()
+            group_subnets.sort()
+
+            # See if anything changed.
+            if (
+                matching_groups['db_subnet_group_name'] != group_name or
+                matching_groups['db_subnet_group_description'] != group_description or
+                existing_subnets != group_subnets
+            ):
+                if not module.check_mode:
+                    # Modify existing group.
+                    try:
+                        connection.modify_db_subnet_group(
+                            aws_retry=True,
+                            DBSubnetGroupName=group_name,
+                            DBSubnetGroupDescription=group_description,
+                            SubnetIds=group_subnets
+                        )
+                    except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
+                        module.fail_json_aws(e, 'Failed to update a subnet group.')
+                subnet_update = True
+        else:
+            if not module.check_mode:
+                try:
+                    connection.create_db_subnet_group(
+                        aws_retry=True,
+                        DBSubnetGroupName=group_name,
+                        DBSubnetGroupDescription=group_description,
+                        SubnetIds=group_subnets,
+                        Tags=_tags
+                    )
+                except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
+                    module.fail_json_aws(e, 'Failed to create a new subnet group.')
+            subnet_update = True
+    elif state == 'absent':
+        if not module.check_mode:
             try:
-                new_group = conn.create_db_subnet_group(
-                    DBSubnetGroupName=group_name, DBSubnetGroupDescription=group_description, SubnetIds=group_subnets)
-                result = create_result(True, new_group.get('DBSubnetGroup'))
-            except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
-                module.fail_json_aws(e, 'Failed to create a new subnet group')
-        module.exit_json(**result)
-    except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:  # pylint: disable=duplicate-except
-        module.fail_json_aws(e, 'Failed to get subnet groups description')
-        # We have one or more subnets at this point.
-    if state == 'absent':
-        try:
-            conn.delete_db_subnet_group(DBSubnetGroupName=group_name)
-            result = create_result(True)
+                connection.delete_db_subnet_group(aws_retry=True, DBSubnetGroupName=group_name)
+            except is_boto3_error_code('DBSubnetGroupNotFoundFault'):
+                module.exit_json(**result)
+            except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:  # pylint: disable=duplicate-except
+                module.fail_json_aws(e, 'Failed to delete a subnet group.')
+        else:
+            subnet_group = get_subnet_group(connection, module)
+            if subnet_group:
+                subnet_update = True
+            result = create_result(subnet_update, subnet_group)
             module.exit_json(**result)
-        except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
-            module.fail_json_aws(e, 'Failed to delete a subnet group')
-
-    # Sort the subnet groups before we compare them
-    existing_subnets = create_subnet_list(matching_groups[0].get('Subnets'))
-    existing_subnets.sort()
-    group_subnets.sort()
-    # See if anything changed.
-    if (matching_groups[0].get('DBSubnetGroupName') == group_name and
-        matching_groups[0].get('DBSubnetGroupDescription') == group_description and
-            existing_subnets == group_subnets):
-        result = create_result(False, matching_groups[0])
-        module.exit_json(**result)
-    # Modify existing group.
-    try:
-        changed_group = conn.modify_db_subnet_group(
-            DBSubnetGroupName=group_name, DBSubnetGroupDescription=group_description, SubnetIds=group_subnets)
-        result = create_result(True, changed_group.get('DBSubnetGroup'))
-        module.exit_json(**result)
-    except (botocore.exceptions.BotoCoreError, botocore.exceptions.ClientError) as e:
-        module.fail_json_aws(e, 'Failed to update a subnet group')
+
+        subnet_update = True
+
+    subnet_group = get_subnet_group(connection, module)
+    changed = tags_update or subnet_update
+    result = create_result(changed, subnet_group)
+    module.exit_json(**result)
 
 
 if __name__ == '__main__':
diff --git a/tests/integration/targets/rds_subnet_group/tasks/main.yml b/tests/integration/targets/rds_subnet_group/tasks/main.yml
index 664d78edeee..ff31d014673 100644
--- a/tests/integration/targets/rds_subnet_group/tasks/main.yml
+++ b/tests/integration/targets/rds_subnet_group/tasks/main.yml
@@ -64,7 +64,7 @@
     register: subnets
 
   - set_fact:
-      subnet_ids: '{{ subnets | community.general.json_query("results[].subnet.id") | list }}'
+      subnet_ids: '{{ subnets.results | map(attribute="subnet.id") | list }}'
 
   # ============================================================
 
diff --git a/tests/integration/targets/rds_subnet_group/tasks/tests.yml b/tests/integration/targets/rds_subnet_group/tasks/tests.yml
index 0b4e3d1b52a..7018448c415 100644
--- a/tests/integration/targets/rds_subnet_group/tasks/tests.yml
+++ b/tests/integration/targets/rds_subnet_group/tasks/tests.yml
@@ -1,8 +1,21 @@
 ---
-# XXX rds_subnet_group doesn't support check_mode yet
-
 # ============================================================
 # Basic creation
+- name: 'Create a subnet group - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
 - name: 'Create a subnet group'
   rds_subnet_group:
     state: present
@@ -23,6 +36,21 @@
     - subnet_ids[0] in result.subnet_group.subnet_ids
     - subnet_ids[1] in result.subnet_group.subnet_ids
 
+- name: 'Create a subnet group (idempotency) - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+
 - name: 'Create a subnet group (idempotency)'
   rds_subnet_group:
     state: present
@@ -45,6 +73,20 @@
 
 # ============================================================
 # Update description
+- name: 'Update subnet group description - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
 
 - name: 'Update subnet group description'
   rds_subnet_group:
@@ -65,6 +107,21 @@
     - result.subnet_group.subnet_ids | length == 2
     - subnet_ids[0] in result.subnet_group.subnet_ids
     - subnet_ids[1] in result.subnet_group.subnet_ids
+  
+- name: 'Update subnet group description (idempotency) - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
 
 - name: 'Update subnet group description (idempotency)'
   rds_subnet_group:
@@ -85,6 +142,21 @@
     - result.subnet_group.subnet_ids | length == 2
     - subnet_ids[0] in result.subnet_group.subnet_ids
     - subnet_ids[1] in result.subnet_group.subnet_ids
+  
+- name: 'Restore subnet group description - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
 
 - name: 'Restore subnet group description'
   rds_subnet_group:
@@ -108,6 +180,20 @@
 
 # ============================================================
 # Update subnets
+- name: 'Update subnet group list - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[2] }}'
+    - '{{ subnet_ids[3] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
 
 - name: 'Update subnet group list'
   rds_subnet_group:
@@ -129,6 +215,21 @@
     - subnet_ids[2] in result.subnet_group.subnet_ids
     - subnet_ids[3] in result.subnet_group.subnet_ids
 
+- name: 'Update subnet group list (idempotency) - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[2] }}'
+    - '{{ subnet_ids[3] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+
 - name: 'Update subnet group list (idempotency)'
   rds_subnet_group:
     state: present
@@ -149,6 +250,23 @@
     - subnet_ids[2] in result.subnet_group.subnet_ids
     - subnet_ids[3] in result.subnet_group.subnet_ids
 
+- name: 'Add more subnets subnet group list - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    - '{{ subnet_ids[2] }}'
+    - '{{ subnet_ids[3] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
 - name: 'Add more subnets subnet group list'
   rds_subnet_group:
     state: present
@@ -173,6 +291,23 @@
     - subnet_ids[2] in result.subnet_group.subnet_ids
     - subnet_ids[3] in result.subnet_group.subnet_ids
 
+- name: 'Add more members to subnet group list (idempotency) - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    - '{{ subnet_ids[2] }}'
+    - '{{ subnet_ids[3] }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+
 - name: 'Add more members to subnet group list (idempotency)'
   rds_subnet_group:
     state: present
@@ -197,8 +332,317 @@
     - subnet_ids[2] in result.subnet_group.subnet_ids
     - subnet_ids[3] in result.subnet_group.subnet_ids
 
+# ============================================================
+# Add tags to subnets
+- name: 'Update subnet with tags - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+      "Tag Two": 'two {{ resource_prefix }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
+- name: 'Update subnet with tags'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+      "Tag Two": 'two {{ resource_prefix }}'
+  register: result
+
+- assert:
+    that:
+    - result is changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 2
+    - result.subnet_group.tags["tag_one"] == '{{ resource_prefix }} One'
+    - result.subnet_group.tags["Tag Two"] == 'two {{ resource_prefix }}'
+  
+- name: 'Update subnet with tags (idempotency) - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+      "Tag Two": 'two {{ resource_prefix }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+
+- name: 'Update subnet with tags (idempotency)'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+      "Tag Two": 'two {{ resource_prefix }}'
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 2
+    - result.subnet_group.tags["tag_one"] == '{{ resource_prefix }} One'
+    - result.subnet_group.tags["Tag Two"] == 'two {{ resource_prefix }}'
+
+- name: 'Update (add/remove) tags - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_three: '{{ resource_prefix }} Three'
+      "Tag Two": 'two {{ resource_prefix }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
+- name: 'Update (add/remove) tags'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      tag_three: '{{ resource_prefix }} Three'
+      "Tag Two": 'two {{ resource_prefix }}'
+  register: result
+
+- assert:
+    that:
+    - result is changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 2
+    - result.subnet_group.tags["tag_three"] == '{{ resource_prefix }} Three'
+    - result.subnet_group.tags["Tag Two"] == 'two {{ resource_prefix }}'
+
+- name: 'Update tags without purge - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    purge_tags: no
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
+- name: 'Update tags without purge'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    purge_tags: no
+    tags:
+      tag_one: '{{ resource_prefix }} One'
+  register: result
+
+- assert:
+    that:
+    - result is changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 3
+    - result.subnet_group.tags["tag_three"] == '{{ resource_prefix }} Three'
+    - result.subnet_group.tags["Tag Two"] == 'two {{ resource_prefix }}'
+    - result.subnet_group.tags["tag_one"] == '{{ resource_prefix }} One'
+
+- name: 'Remove all the tags - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags: {}
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
+- name: 'Remove all the tags'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags: {}
+  register: result
+
+- assert:
+    that:
+    - result is changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+
+- name: 'Update with CamelCase tags - CHECK_MODE'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      "lowercase spaced": 'hello cruel world'
+      "Title Case": 'Hello Cruel World'
+      CamelCase: 'SimpleCamelCase'
+      snake_case: 'simple_snake_case'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
+
+- name: 'Update with CamelCase tags'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+    tags:
+      "lowercase spaced": 'hello cruel world'
+      "Title Case": 'Hello Cruel World'
+      CamelCase: 'SimpleCamelCase'
+      snake_case: 'simple_snake_case'
+  register: result
+
+- assert:
+    that:
+    - result is changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 4
+    - result.subnet_group.tags["lowercase spaced"] == 'hello cruel world'
+    - result.subnet_group.tags["Title Case"] == 'Hello Cruel World'
+    - result.subnet_group.tags["CamelCase"] == 'SimpleCamelCase'
+    - result.subnet_group.tags["snake_case"] == 'simple_snake_case'
+
+- name: 'Do not specify any tag to ensure previous tags are not removed'
+  rds_subnet_group:
+    state: present
+    name: '{{ resource_prefix }}'
+    description: '{{ group_description_changed }}'
+    subnets:
+    - '{{ subnet_ids[0] }}'
+    - '{{ subnet_ids[1] }}'
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+    - result.subnet_group.description == group_description_changed
+    - result.subnet_group.name == resource_prefix
+    - result.subnet_group.vpc_id == vpc.vpc.id
+    - result.subnet_group.subnet_ids | length == 2
+    - subnet_ids[0] in result.subnet_group.subnet_ids
+    - subnet_ids[1] in result.subnet_group.subnet_ids
+    - '"tags" in result.subnet_group'
+    - result.subnet_group.tags | length == 4
+    - result.subnet_group.tags["lowercase spaced"] == 'hello cruel world'
+    - result.subnet_group.tags["Title Case"] == 'Hello Cruel World'
+    - result.subnet_group.tags["CamelCase"] == 'SimpleCamelCase'
+    - result.subnet_group.tags["snake_case"] == 'simple_snake_case'
+
+
 # ============================================================
 # Deletion
+- name: 'Delete a subnet group - CHECK_MODE'
+  rds_subnet_group:
+    state: absent
+    name: '{{ resource_prefix }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is changed
 
 - name: 'Delete a subnet group'
   rds_subnet_group:
@@ -210,6 +654,17 @@
     that:
     - result is changed
 
+- name: 'Delete a subnet group - CHECK_MODE (idempotency)'
+  rds_subnet_group:
+    state: absent
+    name: '{{ resource_prefix }}'
+  check_mode: true
+  register: result
+
+- assert:
+    that:
+    - result is not changed
+
 - name: 'Delete a subnet group (idempotency)'
   rds_subnet_group:
     state: absent