Tax return submission errors

Occasionally, we see an error at the point of tax return submission. We know this can be unsettling, but it’s usually easily explained and can be fixed by you. 

If your HMRC credentials are wrong, you will see:

Authentication Failure. The supplied user credentials failed validation for the requested service. 

You should be able to fix this quickly by double checking the following values entered into APARI:

• Government Gateway ID - in the profile

• Unique Taxpayer Reference - in the profile

• Government Gateway password - entered at the point of submission. You can check your password by logging into your HMRC Online Account and resetting it if necessary.

If it’s your first time doing your own tax return, check your HMRC Online Account. You should see a box called 'Self Assessment'. If not, follow the instructions at the top of the page to 'Add a tax to your account'.

If you’ve already submitted a tax return for the year, you may see:

A submission for the user and tax year has already been successfully made. If amendment(s) are required, you must make an amended submission.    

You can resolve this within APARI by selecting the ‘resubmission’ option at the end of the tax return.

Please wait 72 hours before making the resubmission, as HMRC take time to fully process the initial tax return.

If it’s a little more complicated, you may see:

Your tax return is being reviewed by our tax experts.

Our team will investigate the issue and contact you to fix the issue. The fix is usually straightforward.

To get in touch with our team, please raise a support ticket: