Occasionally MTD users can experience the following error when trying to submit a VAT return:
VAT Return Problem – Invalid Request to WealthWorks Support Service
As the HMRC VAT API link is not valid indefinitely once activated, but for only a set period, it is possible this has expired.
Resolution
Re-activating the HMRC VAT API often refreshes the authorisation token within the browser, and resolves such issues.
To re-activate the link go to WealthWorks+ > Options > Systems Administration > API Configuration > Select HMRC VAT API from the drop down and click Deactivate.
Once deactivated, reselect 'HMRC VAT API' from the drop down list, and select Activate. Re-confirm credentials for the API link to reconnect.
Once this has been done you should then be able to submit the return without further issue.