Insufficient Response to ADRs

12.10.3 – Insufficient Response to ADRs (Rev. 13678; Issued: 03-12-26; Effective: 04-13-26; Implementation: 04-13-26) If the documentation submitted is inadequate to support payment for the service/item billed, or if the CERT review contractor could not conclude that the billed service/item was provided, was provided at the level billed, and/or was medically necessary, the claim is an insufficient documentation error with error code 21 assigned. Error code 21 claims will be posted under the MAC feedback section of the C3HUB. MACs should reach out to the provider or supplier to submit the requested documentation to the CERT review contractor.