Billing for RDS already excluded

If you are being charged for an Amazon RDS (Relational Database Service) instance that you believe you have excluded, there could be a few reasons for this:

1. Billing Cycle: The charges may be reflecting a previous billing cycle, meaning the exclusion settings were applied after the billing period had already started. It's possible that the charges are for the period before the exclusion took effect.
2. Service Modifications: Check if any modifications were made to the RDS instance after the exclusion was applied. If you made changes, such as resizing the instance or modifying its settings, additional charges may apply.
3. Additional Resources: The exclusion you applied might have only affected the base RDS instance but not additional resources associated with it. For example, if you have RDS automated backups or read replicas enabled, these additional resources may still incur charges even if the main instance is excluded.
4. Misconfiguration: Double-check the exclusion settings you applied to ensure they were correctly configured. Review the AWS console or the API/CLI commands you used to exclude the RDS instance and verify that it was done properly.

Let me know if this helps you to find the reason.