Billing when performing cross-account requests?

Hello and thanks for the help!

I was searching for this in the documentation and couldn't find a clear answer: If a role in account A performs an action on a resource in account B (say a GetItemCommand on a DynamoDB Table or a SendMessage on a SQS queue), is the action billed to the account A or account B, or both?

I'm 99% sure it's billed to the account B, but I want it to make 100%, thank you :)

Thomas