Help! My submission failed

So you've completed your tax return, and hit submit only to get an error message. A couple of suggestions and how to fix it.

So long as you've got your UTR (you can check your UTR here), you should look at using untied express submit. untied express submit enables you to file without needing your own HMRC login. You will need to send us two forms of ID – one with a photo and a different one with your address to This can take us 24 hours to process, but we aim to reply faster. We will then enable this on your account. 

More information on possible errors is given below.

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

    This  is a message from HMRC and suggests an error in one of the following areas. If you get this:
    • Double check your Government Gateway / HMRC login username and password by following the links to sign in here (see below if they don't work)
    • Having logged into your Government Gateway account, check that you are registered for self assessment. If you're not, then do so!
    • Double check your Unique Taxpayer Reference number (format is ten digits 1234567890)
    • It's also good to double check your National Insurance Number (format is two letters, six digits, one letter AB123456C)
    • If your HMRC username is more than 12 characters long try entering only the first 12 characters in untied.
  • You may also get an error that the untied calculation isn't agreeing with HMRC's data in which case please get in touch and we will look into it.

If you don't know your Government Gateway login, follow the HMRC instructions you get by clicking through here to recover your details. If you are using a third party service as part of GOV.UK Verify, you cannot use this login to file directly with untied. Please contact us and we will outline the procedure that you need to take.

Some of these recovery methods can take up to two weeks, so checking early is a very good idea!

If you continue to have authentication problems and/or have not set up your HMRC account for self assessment, we may still be able to help - contact us for details.

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