If you joined Making Tax Digital in April 2026, it is easy to assume your old tax return has gone. It has not. Your 2025/26 self assessment return is still due by 31 January 2027, in the normal way.
Why you still file a return
MTD for Income Tax started with the 2026/27 tax year. Everything before 6 April 2026 is under the old rules. So this January looks like every other January: a 2025/26 return, filed online, with any tax owed paid the same day.
What is due on 31 January 2027
- Your 2025/26 tax return, filed online.
- The balance of tax owed for 2025/26.
- Your first payment on account for 2026/27, if you make them.
The existing penalties apply to this return, not the new MTD points system. If it is late, the £100 penalty applies straight away. Our post on payments on account explains why January is often bigger than expected.
When the final declaration starts
Your first MTD final declaration covers 2026/27 and is due by 31 January 2028. That is when the quarterly updates are brought together with everything else: other income, reliefs and adjustments.
Two things to watch
First, do not let the quarterly updates crowd out the return. 7 November and 31 January sit close together. Second, the figures on your 2025/26 return feed straight into your payments on account for 2026/27, so get them right.
We prepare self assessment returns and MTD filings together, so nothing falls between them. See our personal tax and Making Tax Digital pages.
