If you receive this code it's because:

HMRC holds different details to what has been inputted into Capium prior to the submission attempt


There is a block on your HMRC account.

We advise you check the below:

Your companies House Presenter ID - The Presenter Identifier starts with 000 and ends with 000, is a mixture of numbers and letters and is 11 characters long. This is usually entered in capitals.

You Company authentication code - 6 digit

You Company's Government gateway credentials -  Can be up to 12 characters

More information can be found here: https://capium.freshdesk.com/a/solutions/articles/9000236664

If the above login credentials are correct we advise that the best course of action is to contact HMRC.