Hi hillsmixtape_andy, thanks for reaching out to the Community today
We'd like to make sure that you're able to submit your VAT return in QuickBooks.
The most possible causes for MTD errors are that the credentials used to connect QBO to HMRC for MTD are not authorised (for the VAT Reg number entered in the Tax settings) or the user is the wrong user type (e.g. a client accessing the VAT center to submit the return when it is on ASA only, or an accountant accessing it when it is not set up on ASA).
Please note: The authorisation process will accept PAYE credentials as well as VAT credentials. Please confirm that the credentials entered in QuickBooks are correct and that you're able to sign into your HMRC account online using these.
If you are an accountant, please check the URL in the address bar of the browser for errorCode=LOST_OAUTH_ERROR after selecting Learn More.
This means that QuickBooks has lost authorisation to submit on behalf of your client and you will need to disconnect and reconnect your ASA. In QBO Accountant, see Company settings > Advanced > Making Tax Digital for your clients to disconnect.
If you're still unable to submit, please get back in touch below with the type of user you're accessing as (e.g. QuickBooks Online Primary Admin or QuickBooks Online Accountant) and if the company was registered for MTD under an Agent Services Account.
