Fix HMRC Agent Auth Error: NO_PERMISSION_ON_AGENCY

If you see the error "HMRC Agent Auth API HTTP 403 [NO_PERMISSION_ON_AGENCY]: The user that is signed in cannot access this authorisation request. Their details do not match the agent business that created the authorisation request" when managing client authorisations in TinyTax, this comes from HMRC's Agent Authorisation API, not from TinyTax itself.

What this error means

HMRC's Making Tax Digital (MTD) Agent Authorisation service requires that the agent who accesses or manages an authorisation invitation is the same agent who created it — identified by the HMRC Agent Services Account (ASA) connected via OAuth.

If the HMRC connection in TinyTax is authenticated with a different Agent Services Account than the one that originally created the invitation, HMRC will return this 403 error.

Common causes

1. Multiple HMRC Agent Services Accounts — if your firm has more than one ASA (for example, one for MTD-VAT and another for older services, or one created by a different staff member), and TinyTax is connected to a different one than the account that created the invitation.

1. Re-authenticated with a different account — if you disconnected and reconnected your HMRC credentials in TinyTax using a different login than the one originally used.

1. Invitation created outside TinyTax — if the authorisation request was created directly in HMRC's Agent Services portal rather than through TinyTax, and the accounts do not match.

How to fix it

1. Identify which HMRC Agent Services Account created the authorisation request. Log into HMRC Online Services for Agents at tax.service.gov.uk/agent-services-account and check which account holds the pending invitation.

1. Reconnect TinyTax with that account. In TinyTax, go to your account settings and disconnect your current HMRC connection, then reconnect using the correct Agent Services Account credentials.

1. If you need to use a fresh invitation, create a new authorisation request from within TinyTax once you have reconnected with the correct account. The new invitation will be tied to the currently connected ASA.

If the problem persists

If you are certain you are using the correct Agent Services Account and still see this error, it is possible HMRC's records for the invitation have expired or the invitation was created with a different ARN (Agent Reference Number). Contact HMRC's helpline on 0300 200 3410 and ask them to confirm the ARN associated with the authorisation request.