While authenticating with HMRC or submit a VAT return, the following message may appear: 

This can occur when:

• The company VAT registration number in Accounting isn't linked to the Government Gateway user ID you've authenticated with - To check the VAT registration number, go to More, then Business Settings and Accounting Dates & VAT
• The Government Gateway credentials weren't correct when you authenticated - To check this, go to the Government Gateway and ensure you can sign in using the same ID and password

Check the following:

1. Make sure your VAT number is correct within your settings.
2. Go to the HMRC website and sign in to your Government Gateway account that relates to your VAT account. 
3. If you can sign in successfully, make sure you are using the same details to authenticate in Sage Accounting. 
4. If you can't sign in to Government Gateway, contact HMRC for further support. 
5. If everything is correct, and you can sign in, try again to authenticate.
6. If you are still receiving the error, check Sign up your client for Making Tax Digital for VAT.

 NOTE: If you've migrated from another Sage product, you'll need to connect to HMRC and not use the reauthenticate option.

If you have checked all of the information above and are still receiving the error, please contact HMRC (opens in new tab).