Cost of not running resources

There are a few potential reasons why you might be seeing small charges for RDS and VPC even if you don't have any actively running resources:

1. For RDS:

   • You may have snapshots or automated backups still stored, which can incur storage costs even after instances are deleted.
   • There might be retained automated backups from recently deleted instances.

2. For VPC:

   • AWS started charging for public IPv4 addresses from February 2022. Even if you're not actively using them, allocated public IPs can result in charges.
   • You may have Elastic IP addresses that are not attached to running instances but are still allocated to your account.
   • There could be other VPC components like NAT Gateways, network interfaces, or even inactive resources like Route Tables and Internet Gateways that can attract small maintenance charges.

To address these issues:

• Use the AWS Cost Explorer to analyze your costs in detail and identify which specific resources are generating charges.
• Check for any forgotten resources across all regions in your AWS account.
• For RDS, review and delete any unnecessary snapshots or adjust backup retention settings.
• For VPC, release any unused public IPs or Elastic IPs, and delete any unnecessary network components.

If you've taken these steps and still see unexpected charges, it may be worth contacting AWS Support for a more detailed investigation of your account, as there could potentially be a billing error.
Sources
Abnormal Billing for the Free Resources | AWS re:Post
iam not using vpc | AWS re:Post
Billing regarding my vpc | AWS re:Post
To stop RDS from billing | AWS re:Post