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FeaturesMaking Tax DigitalUpdated April 1, 2026

Fix: Unauthorised Error When Submitting Data to HMRC

Fix: Unauthorised Error When Submitting Data to HMRC

Release: v1.0.478
Type: Bug Fix


What Happened

Some users encountered an error notification appearing in the bottom-right corner of the screen when attempting to send data to HMRC. Rather than the submission completing as expected, the process would fail and surface this error — leaving it unclear whether data had been sent or not.

After investigation, the issue was identified as an unauthorised (401) error occurring during the HMRC submission request. This type of error had been seen in earlier testing phases and pointed to a problem with how authentication credentials were being handled or passed during the submission flow.

What Was Fixed

The cause of the unauthorised error in the HMRC data submission path has been located and resolved. The fix ensures that valid credentials are correctly included when requests are made to HMRC, preventing the 401 rejection and allowing submissions to complete as intended.

What You Should See Now

  • Submitting data to HMRC (quarterly updates, annual summaries, final declarations) completes without triggering an error notification.
  • The bottom-right error toast no longer appears during a normal submission flow.
  • If a genuine authentication issue occurs (e.g. an expired HMRC OAuth token), you will still be prompted to re-authorise — this is expected behaviour.

Action Required

No action is required on your part. If you previously experienced failed submissions due to this error, please retry your submission — it should now go through successfully.

If you continue to see errors after this update, please check that your HMRC connection is still active under Settings → HMRC Connection, and re-authorise if prompted.


Released as part of v1.0.478.