Self Assessment error message: authentication failure

This article explains the steps to take if you've received an error message telling you there is a problem with your submission when trying to file your Self Assessment return in FreeAgent.

If HMRC does not recognise the Government Gateway credentials that you have entered, you’ll receive the error message below when trying to submit your Self Assessment return to HMRC.


There can be a few other reasons for this error message. If you have full (level 8) access to your FreeAgent account, you can follow the steps below to identify and resolve the error.

1. Check that your unique tax reference is correct

Select 'Settings' from the drop-down menu in the top-right corner and then select 'Users'.


Select your user profile and make sure that the ‘Unique Tax Reference’ (UTR) is correct. Please make sure that you're using your personal UTR and not your limited company UTR or the UTR of any other individual, such as a business partner.

If your UTR is incorrect, update it with the correct number and select ‘Save Changes’. Find out more about how to edit a user profile.

UTR User Details.png

2. Check whether you’ve previously filed Self Assessment using the same Government Gateway credentials

If your accountant has previously filed Self Assessment on your behalf using the credentials that you’re entering into FreeAgent, you may need to register for a new Government Gateway ID (HMRC online account) to file Self Assessment yourself.

3. Check that you can log in to your HMRC online account using the Government Gateway credentials

Navigate to HMRC’s website to check if you can log in to your HMRC online account using the same Government Gateway credentials that you’re entering into FreeAgent. If you’re unable to log in, please see the following HMRC guidance.

4. Check that Self Assessment has been enabled as a service

If you can log in to your HMRC online account, make sure that Self Assessment has been enabled as a service. If it has, it should look similar to the image below.


If Self Assessment hasn’t been enabled as a service, you’ll need to select ‘get online access to a tax, duty or scheme’ and follow the steps provided to add it. Please note that if you do need to do this, HMRC will send an activation code out in the post which can take up to 10 days to arrive. Once you’ve successfully enabled online filing, you’ll see a notification advising of return deadlines.

Business tax account Add Self Assesment as a tax.png

If you haven’t filed a Self Assessment return yourself before, for example if your accountant was doing this for you previously, you may need to log in to your HMRC online account and authorise Self Assessment as a service.

5. Check that you’re entering your Government Gateway credentials manually

When submitting your Self Assessment return through FreeAgent, make sure that your Government Gateway credentials are being entered manually and not being auto-filled by your browser.

If any of your details are being auto-filled, you should delete the auto-filled information and enter your Government Gateway ID and password manually instead, just as you would enter it to access your HMRC online account.

In the majority of cases, the authentication failure error message is caused by Self Assessment not being enabled as a service on the HMRC online account, the credentials in FreeAgent being auto-filled or not being the same credentials used to access the HMRC online account.

If you continue to receive the error message after completing the troubleshooting steps above, please check with HMRC directly. As the error message has been sent from their system, they will need to investigate.

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