How do I resolve error code 403 (Unable to return obligation data)?

This is an HMRC error code. As an individual or business using MTDfVAT, you must have subscribed to the MTD for VAT service with HMRC. If you haven’t signed up yet then you will encounter error 403. Please follow this link to sign up to MTD for VAT.

There could also be an issue with the HMRC MTD service.