Utilize Tag Editor to apply tags to existing resources. Establish cost allocation tags to specify the cost center and project ID, allowing 24 hours for these tags to be reflected in the billing data.

Implement an AWS Config rule to notify the finance department of resources without tags. Develop a centralized AWS Lambda solution that uses a cross-account role to periodically tag untagged RDS databases and DynamoDB resources every hour.

Employ Tag Editor to tag existing resources. Set up cost allocation tags to identify the cost center and project ID. Enforce Service Control Policies (SCPs) to prevent the creation of resources that lack the required cost center and project ID tags.

Define cost allocation tags for the cost center and project ID, allowing 24 hours for these tags to update in the billing data. Modify existing federated roles to limit the ability to provision resources that do not adhere to the tagging requirements for cost center and project ID.