Unexpected Charges for Amazon RDS Backup Storage — No Automated Backups Found

There are several possible reasons why you're seeing charges for "Amazon Relational Database Service Backup Storage" even when you can't find any automated backups:

1. Resources in different regions: Check all AWS regions for RDS resources, snapshots, or backups. The charges might be coming from a region you don't typically use.

2. Hidden snapshots: Look carefully through all snapshot tabs in the RDS console, including automated backups that might have been created during deletion of previous instances.

3. Backup retention from deleted instances: AWS may retain automated backups for a period after instances are deleted, which can still incur charges.

4. Delayed billing updates: AWS billing can sometimes have a delay in reflecting changes, so charges might appear for usage that occurred before deletion.

To troubleshoot this issue:

• Use AWS Cost Explorer to identify exactly what RDS features are being charged. Filter by "Service" (select RDS) and "Dimension" (select "Usage Type") to see detailed information.

• Check Cost Explorer with daily granularity to better observe what you're spending money on.

• For your active RDS instance, check if the "Automated backup retention period" is set higher than needed. You can modify this setting to "0 days" to stop creating new backups.

• Look for any RDS proxies or other related services that might still be active.

• Check all regions thoroughly for any forgotten RDS resources, snapshots, or replicas.

If after these steps you still can't identify the source of the charges, contacting AWS Support through the "Account and billing" option in our Support Center would be your best course of action. They can help identify the specific resources causing the unexpected charges: go.aws/support-center.
Sources
I am still being charged for a AWS RDS even though i have deleted the database and any snapshots. | AWS re:Post
To stop RDS from billing | AWS re:Post
I would like to stop an active service and cannot find it | AWS re:Post
Why am I being charged money on my account? | AWS re:Post

I would suggest to please check below details to identify this cost :

1. In your billing first identify region in which this charge occurs, If you are not able to identify region then check Cost explorer and filter by service "Amazon Relational Database Service" and scroll down to bottom where cost details are in broken format and see the region in which this charge occur. 
2. Once you have region, just login to Aurora and RDS console and select that region
3. Now in left navigation pane select snapshots and check TABS (Manual, System, Shared with me and Backup Service) see if you have any backup there. 
4. Now from left navigation pane select Automated Backups and check TABS (Current Region, Replicated, Retained) see if any backup there. 

If you are still not able to find any backup then kindly reach out to AWS support team and share your account ID and region in which you are getting bill for RDS snapshots.

Hope it helps and if it does, I would appreciate if answer can be accepted so that community can benefit for clarity when searching for similar enquiries in repost/aws guide.