steps to enable and use Cost Allocation Tags in the AWS Billing Console

To enable and use Cost Allocation Tags in the AWS Billing Console, follow these steps:

1. Create and apply tags to your AWS resources using the Tag Editor or API. These are your user-defined cost allocation tags.

2. Sign in to the AWS Billing and Cost Management console.

3. Navigate to the "Cost Allocation Tags" page in the navigation pane.

4. Find the tags you want to activate by using the filter functionality if needed.

5. Select the tag keys you want to activate.

6. Choose "Activate" to enable these tags for cost allocation tracking.

7. Wait for the tags to appear in your cost allocation reports. Note that it can take up to 24 hours for tag keys to appear and activate.

Important things to know:

• Cost allocation tags only appear after you've enabled services like Cost Explorer, Budgets, or AWS Cost and Usage Reports.
• Tags are not applied retroactively to resources created before the tags were created.
• User-defined tags will have the prefix "user:" in cost allocation reports.
• Each tag key should only be used once for each resource.
• If you're working with an AWS solution, you may need to activate specific tags like "AppManagerCFNStackKey" to track solution costs.
• Cost allocation tags can only be activated from the management account for an organization.
• You can also use the UpdateCostAllocationTagsStatus API operation to activate tags in bulk.
  Sources
  Activating user-defined cost allocation tags - AWS Billing
  Using user-defined cost allocation tags - AWS Billing
  Activate cost allocation tags associated with the solution - Connected Mobility Solution on AWS