Check the following common causes:

You incurred the charges earlier in the billing cycle

If you ran an EC2 instance at the beginning of the month, but you stopped or terminated it later, your bill will include charges for the time that the instance was running.

You terminated your instances, but you still have EC2 resources provisioned to your account

The Elastic Compute Cloud line item in your bill includes resources other than instances. EC2 instances are often used along with other EC2 resources, such as:

Elastic IP addresses

Amazon Elastic Block Store (Amazon EBS) volumes

Expand the Elastic Compute Cloud

line item in the Billing and Cost Management console to see your EC2 usage by resource. Then, open the EC2 console and terminate or delete any resources that you don't need.

Note: Stopped instances do not incur charges, but Elastic IP addresses or EBS volumes attached to those instances do.

You terminated your instances in one Region, but you also have instances running in another Region

Expand the Elastic Compute Cloud line item in the Billing and Cost Management console, and check if you have resources in other EC2 regions. Then, open the EC2 console, and terminate or delete any resources you don't need.

New instances have launched on your account

Services such as Auto Scaling and Elastic Beanstalk can launch instances automatically based on how you configured them. Spot bids launch instances when a certain Spot bid price is met.

Check that service's documentation for more information on terminating these resources. If you're unsure which service or resource is launching instances on your account, contact AWS Support for help.

You purchased a Reserved Instance

Reserved Instances are billed each month for each hour in a given month until the end of the Reserved Instance contract.

If you're no longer using an instance type, modify any applicable Reserved Instances to sizes that suit your current use case. You can also sell your instance on the Reserved Instance Marketplace.

If none of these scenarios apply to you, or you're not sure why you're being billed, contact AWS Support.