1046 Authentication error when filing since June 2020

If you are receiving a 1046 HMRC authentication error when trying to file an individual (SA100), partnership (SA800), trust (SA900), corporation tax (CT600) or non MTD VAT return and you fall into either of the following categories, you may need to take action.

• You’ve recently changed your government gateway password and it now includes uppercase characters
• You haven’t changed your government gateway password recently, but the password entered into TaxCalc isn’t identical to the one used to access your government gateway

At the end of June 2020, HMRC made changes to the passwords that can be used with the government gateway.  On the whole, this gives more flexibility in the type and the number of characters that can be used and also allows for upper and lower case characters to be used. 

What do I need to do?

I’ve recently changed my password

If your government gateway password contains upper case characters and you need to file a return before our next software update (due in August), you will need to amend your password to all lowercase characters.

1. Go to the HMRC Login page: https://www.tax.service.gov.uk/gg/sign-in.
2. Click on: 'I have forgotten my password' and follow the instructions to receive a code and link via email.

Once you have changed your password for your HMRC gateway account, please ensure you update your filing credentials within TaxCalc:

For individual users:

1. Open your tax return in TaxCalc.
2. Remove and re-enter the password (tick ‘Show password’ to see the password as you type it).
3. Re-submit the return by going to Check and Finish > File Online > Re-submit.

For agents:

1. Go to Admin Centre>Applications
2. Double click on Tax Return Production>choose Filing credentials
3. Remove and re-enter the password for the services the password relates to: Individuals, Partnerships and Trusts (SA100, SA800, SA900) and/or Corporation (CT600)
4. Click on Close and save.
5. Repeat 2 to 6 for VAT Filer.

If users also have their own filing credentials:

1. Go to Admin>Users
2. Double click on the user>choose Online filing settings
3. Remove and re-enter the password

Once the filing credentials have been updated here, when you are filing existing returns, please ensure the credentials are 'refreshed' on the Filing screen by un-ticking the radio button which explains which credentials to use by clicking on another option and then re-ticking the correct option.For example if 'Use my firm's gateway credentials' is ticked, tick another option such as 'Use my User's gateway credentials' then re-tick 'Use my firm's gateway credentials'. This ensure the credentials are updated from the changes made in Admin Centre.

I haven’t changed my password recently

If you haven’t recently changed your password but are getting a 1046 error, it might be because the way it’s been shown in TaxCalc is not identical to the government gateway.  This will more than likely be because you have entered the password into TaxCalc and some of the characters have been entered as Uppercase.  Although this would not previously have caused an issue, HMRC’s new rules include case sensitivity and so our software now needs to consider this change.

To correct the issue, you’ll need to re-enter your password into TaxCalc without any Uppercase characters by following the instructions above to update your filing credentials in TaxCalc.