Effective billing date - AWS Billing and Cost Management

Effective billing date

When the member account owner accepts your request to join the organization, you immediately become responsible for the member account's charges. If the member account joins in the middle of the month, the management account is billed only for the latter part of the month.

For example, if a member account joins an organization on March 10, then AWS bills the management account for the member account’s period of usage starting on March 10. The member account's original owner is still billed for the first part of the month.