User-defined tag restrictions - AWS Billing

User-defined tag restrictions

For basic tag restrictions, see Tag Restrictions in the Amazon EC2 User Guide.

The following restrictions apply to user-defined tags for Cost Allocation:

  • The reserved prefix is aws:.

    AWS generated tag names and values are automatically assigned the aws: prefix, which you can't assign. User-defined tag names have the prefix user: in the cost allocation report.

  • Use each key only once for each resource. If you attempt to use the same key twice on the same resource, your request will be rejected.

  • In some services, you can tag a resource when you create it. For more information, see the documentation for the service where you want to tag resources.

  • You can't backdate the application of a tag. This means that tags only start appearing on your cost allocation report after you apply them and don't appear on earlier reports.

  • If you need characters outside of those listed in Tag Restrictions, you can apply standard base-64 encoding to your tag. Billing and Cost Management does not encode or decode your tag for you.

  • User-defined tags on non-metered services can be activated (for example, Account Tagging). However, these tags will not populate in the Cost Management suite because these services are not metered.