Self Assessment

Error 1046 -What It Means and How to Fix It

Error 1046 -What It Means and How to Fix It

  • December 09, 2025


HMRC Error 1046 is a common issue that appears when filing your Self-Assessment return online. It usually means HMRC cannot verify the login details or tax information you have submitted. Although it looks technical, the cause is normally simple and quick to fix.

 

What Is Error 1046?

Error 1046 occurs when HMRC cannot match your Government Gateway credentials or personal tax details with their records. This often happens due to incorrect login information, missing Self-Assessment activation, or outdated personal details.

 

Common Causes

The error is usually because of one of the following:

  • Incorrect Government Gateway User ID or password
  • Self-Assessment not activated on your Gateway account.
  • Incorrect UTR or personal details (name, NI number, address)
  • Account temporarily locked after multiple failed logins
  • Browser issues, such as auto fill, cache or cookies inserting incorrect information.

 

How to Fix HMRC Error 1046

Most people resolve the issue by following these steps:

  1. Log in directly to your Government Gateway account.

          If you cannot log in, reset your credentials.

  1. Re-enter your login details manually (do not copy/paste or use auto fill).
  2. Check that Self-Assessment is activated under ‘Your Services’ in your gateway account.

          If not, add the service, enter your UTR and activation code.

  1. Confirm your UTR and personal details match HMRC’s records exactly.
  2. Use a fresh browser session or incognito mode to avoid auto fill and cache issues.
  3. Wait for any temporary lock to clear before trying again.
  4. Contact HMRC Online Services if the error persists, they can check whether your account or UTR is correctly linked.

 

In Summary

Error 1046 usually comes down to a simple mismatch in login details or tax information. By checking your credentials, confirming your Self-Assessment setup, and ensuring your UTR and personal details are correct, you can fix the issue quickly and submit your Personal Tax Return without further hassle.