Do you still need to file a Self Assessment return in January 2027?
Yes. If you are in MTD's first wave, you still file a normal 2025/26 Self Assessment return by 31 January 2027. That's separate from your new MTD obligations, which started 6 April 2026, and separate from your first Final Declaration, not due until 31 January 2028.
What this means for you
Making Tax Digital doesn't retroactively change how your last pre-MTD tax year is taxed. 2025/26 is filed exactly the way Self Assessment has always worked: online, through HMRC's website or your accountant's software, by 31 January 2027.
Meanwhile, your MTD obligations for 2026/27 run alongside and after that: quarterly updates through the year, then a Final Declaration (MTD's replacement for the Self Assessment return) that finalises 2026/27 itself. That's not due until 31 January 2028, over a year after your last old-style return.
The one thing people get wrong: assuming MTD replaces Self Assessment immediately
It's easy to assume that once MTD starts, the old system stops straight away. For your transition year, both run side by side. One filing closes out the year before MTD. The other builds up through your first MTD year. This overlap is one of the most confusing parts of the whole transition, so it's worth marking both dates separately rather than treating them as one event.
Common questions
What is the difference between this return and my Final Declaration?
The 31 January 2027 filing is your last old-style Self Assessment return, for 2025/26, filed the normal way online. Your Final Declaration is the new MTD equivalent, for 2026/27, filed through MTD software, and is not due until 31 January 2028.
Do I pay tax twice around this time?
No. Each filing relates to a different tax year, and normal payment dates apply throughout. Balancing payments and payments on account are unchanged by MTD.
Does this collision happen for every wave?
Yes, in the year each wave starts. Wave 2 files a normal 2026/27 return by 31 January 2028, and wave 3 files a normal 2027/28 return by 31 January 2029. Each is a one-off transition, not a recurring event.
Do I use MTD software for this last old-style return?
No. It is filed the normal Self Assessment way. MTD software is only for your new quarterly updates and Final Declaration, which start separately.