HMRC's message · HTTP 400
Finalisation cannot occur until after the end of the tax year
When it appears
Triggering a final calculation before 6 April.
What to check
- The tax year selected.
How to fix it
Wait until after 5 April.
Making Tax Digital in Accountin
Accountin shows HMRC's code and message next to a plain explanation, and keeps HMRC's reply against every submission.