I am getting a message saying that I need to ''Grant authority'' but I have already done this Mtd-69

Absolute Excel VAT Filer  

When you first file your VAT return for either yourself or on behalf of a client you have to grant authority to HMRC, this authority only lasts for an 18 month period so if when you are trying to file a VAT return you again get the message it simply means that the 18 month period has lapsed and you will need to re grant permission.

When the HMRC pages comes up on screen simply scroll to the bottom of the page and click the green continue button and follow the on screen prompts.

If you are filing as an agent then you will need to log onto your Agent Services account (ASA) and then re grant authority for Absolute to interact with HMRC - you can do this by clicking on the following link https://www.gov.uk/guidance/sign-in-to-your-agent-services-account

Please note that the credentials that you use to log in will NOT be the same as your Government Gateway credentials.