HMRC's message · HTTP 400
Period summary overlaps with any of the existing period summaries
When it appears
Sending a quarterly update for self-employment or property income.
What to check
- The updates HMRC already holds for the business this year.
- Whether the period type was changed after an update was sent.
How to fix it
Adjust the dates so the update covers only the days not yet reported, or amend the existing update instead.
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.