The authentication failure error message indicates that some of the required user credentials are missing or incorrect. If you have recently updated your HMRC Gateway credentials, you will need to update them in Access Payroll. To do this, follow the steps below.
Click System, and then click Company.
Click the HMRC Returns tab, and click Edit.
Make a note of the User ID.
Remove the information in the User ID and Password fields, and click Save.
Click Edit, enter your User ID and Password.
📌Note: The credentials you use will need to match those used for the HMRC gateway.
Click Save.