HMRC's message · HTTP 400
A calculation is in progress. Please wait before triggering a new calculation
When it appears
Triggering a tax calculation.
What to check
- Whether the previous calculation has finished.
How to fix it
Wait a short while, then retrieve the calculation or trigger a new one.
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.