The MTD Notebook · Self Assessment · 11 August 2026

Does MTD replace your Self Assessment tax return?

The single most common thing people believe about Making Tax Digital is that it means “no more tax return.” It does not. You still file a tax return every year, still by 31 January, still declaring every source of income you have. What changes is how you file it — and the four quarterly updates people fixate on are not it. Here is what actually replaces the old online form, and what stays exactly the same — every point checked against GOV.UK and dated.

1. The short answer

Making Tax Digital for Income Tax does not abolish the Self Assessment tax return. It replaces the way you produce and send it. Instead of logging into HMRC once a year and typing figures into the online Self Assessment form, you keep digital records, send HMRC four quarterly updates during the year, and then finish the year with a tax return submitted from your software. That final return — which the underlying rules and much of the software still call the final declaration — is where your tax is actually worked out and where the amount you owe is settled.

2. Two steps, not one: updates and the return

The confusion comes from treating the quarterly updates as if they were mini tax returns. GOV.UK is unusually blunt that they are not:

An update is your software adding up the digital records for a business and sending HMRC the running totals of income and expenses. You make no accounting or tax adjustments before sending one — no capital allowances, no private-use split, no reliefs. It is a rough progress report. The real work happens once, at the end:

• Quarterly updates (×4) — summaries of your self-employment and property income and expenses, due 7 August, 7 November, 7 February and 7 May. No adjustments, no tax calculated.
• The year-end tax return / final declaration (×1) — where you make every adjustment and claim, add all your other income, confirm the figures are complete and correct, and see the tax due. This is the step that replaces the old Self Assessment return.

And the two are linked in one direction that trips people up: GOV.UK states you must send your quarterly updates before you can submit your tax return. Skip the summaries and the front door to the return stays shut.

3. Same deadline, new front door

Here is the part that should be reassuring. The date has not moved. Your MTD tax return is due by the same 31 January that Self Assessment always used:

GOV.UK gives the window plainly: you can submit the 2025 to 2026 return “at any time from 6 April 2026 to 31 January 2027,” and the same shape applies every year after. So for your first mandated year, 2026/27, the return is due by 31 January 2028 — and, exactly as before, that is also the day the tax itself is due. The mechanism is new; the two dates you have always cared about are not.

4. Everything else still goes on the return

The quarterly updates only ever cover your self-employment and property income. That is a small slice of most people’s tax picture, and it is why the return still matters as much as it ever did. Before you can submit, GOV.UK says you must make sure all your other taxable income and gains for the year are included in your software. In practice:

• Some HMRC adds for you. If HMRC already holds the information — employment income and tax under PAYE, certain pensions and benefits — it pre-populates your return. You must still check it before you submit.
• The rest you add yourself. Dividends, savings and investment interest, capital gains, and any other income HMRC does not already have are your job to enter. Miss them and the return is wrong, whatever the quarterly updates said.

This is the heart of why “MTD means no more tax return” is a dangerous myth. If you have a salary and a side business, or a rental and a share portfolio, the annual return is still the only place your whole position comes together and the tax is calculated. The quarterly updates never see most of it.

A useful footnote from the guidance: you can amend a submitted return within 12 months of its deadline through your software, and a refund is not claimed inside the MTD return — that is a separate process. So a good-faith mistake is fixable; it is not a one-shot form.

5. Your last old-style return, then the switch

Nobody files two returns for the same year. GOV.UK sets out the hand-over cleanly: you still submit a normal Self Assessment return, the way you always have, for the tax year before you start using MTD. For tax years after that, you use your MTD software to complete and submit the return instead.

So for someone mandated from April 2026 (qualifying income over £50,000), the timeline is:

• 2025/26 — your last old-style Self Assessment return, filed the usual way by 31 January 2027. This is also the return whose figures decide whether you were mandated in the first place.
• 2026/27 — your first MTD year: four quarterly updates, then a tax return submitted from your software by 31 January 2028.

One return per year throughout. The form you use changes exactly once, at the boundary.

6. The return still carries a filing penalty — even this year

You may have read that MTD deadlines are penalty-free in the first year. That is true of the quarterly updates — and only them. GOV.UK is specific: HMRC will not apply penalty points for late quarterly updates during 2026/27, but penalty points still apply for late tax returns for this tax year. The year-end return is exactly the submission that first-year softness does not cover.

It is one penalty point per late return, and for the mandated (over £50,000) cohort it takes four points before a £200 penalty is due — so a single slip is not a fine. But the return is the one MTD submission that can put a point on your record this year, and paying the resulting bill late is a separate, percentage-based charge on top. We pulled both systems apart, with the numbers, in a companion post.

7. What to actually do about it

The honest summary for someone in the first mandated wave:

• Expect one return a year, on the same date. MTD adds four in-year summaries; it does not remove the annual return or move 31 January.
• Keep a running total of the whole picture, not just the business. Dividends, interest and gains still land on the return, so track them as you go rather than hunting for them the following January.
• Know the number before the return confirms it. The tax is calculated at the final declaration and due the same day. Working out roughly what you owe as the year runs is the difference between a bill you have saved for and a bill that becomes a late-payment penalty.