You can now use cost allocation tags to manage your Amazon Simple Notification Service (SNS) costs. Cost allocation tags are key-value pairs that let you categorize SNS topics to easily identify their purpose and track associated costs. For example, you may use tags to identify the Amazon SNS topics for a particular department, project, or application.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/05/amazon-sns-adds-support-for-cost-allocation-tags/