If you're a landlord or sole trader moving onto Making Tax Digital for Income Tax (MTD for IT), you've probably been told your Self Assessment return is going away. That's true, but it's easy to misread what's actually happening.
You don't stop telling HMRC how much tax you owe. You do it in a new way, with a different name, at the end of a year that now also includes quarterly updates.
This guide explains exactly what the final declaration is, how it differs from the old Self Assessment return, what it doesn't change (the 31 January deadline, for one), and how the two halves of MTD fit together. It's written for landlords and self-employed people caught by the new rules, with a worked example and a year-by-year deadline calendar.
What is the final declaration under MTD for Income Tax?
The final declaration is the end-of-year submission that replaces the Self Assessment tax return for people in MTD for Income Tax. You make it after your quarterly updates, it's where you finalise your figures and claim your reliefs, and it's due by 31 January following the end of the tax year.
So the deadline you already know hasn't moved. What's changed is the route to it.
Under the old system, you filed one Self Assessment return a year covering everything. Under MTD for IT you do two distinct things in a tax year:
- Quarterly updates of your business income and expenses, sent from your software during the year.
- A final declaration after the year ends, where you bring everything together, add your other income, claim your reliefs and allowances, and confirm the figures are correct.
HMRC's guidance puts it plainly: the information you give at the final declaration "will generate your Self Assessment tax bill for that tax year." It is, in substance, your tax return, just renamed and reached by a new path.
How is the final declaration different from a Self Assessment return?
The honest answer is that the final declaration does the same job. It's the differences in how you get there, and in the tools you're allowed to use, that matter.
| Feature | Old Self Assessment return | Final declaration under MTD for IT |
|---|---|---|
| What it is | One annual return covering all income | The end-of-year submission that finalises your tax |
| How you file | HMRC online account or paper | MTD-compatible software (no paper, no HMRC online return) |
| During the year | Nothing required until the return | Cumulative quarterly updates of business income and expenses |
| Records | No legal format required | Digital records, with digital links between programs |
| Where reliefs are claimed | On the return | On the final declaration |
| Deadline | 31 January after the tax year | 31 January after the tax year (unchanged) |
| Covers other income (employment, dividends, savings) | Yes | Yes, added at the final declaration |
Two practical points are worth drawing out.
First, the paper return and the familiar "fill in your Self Assessment online" journey go away once you're mandated into MTD. Both the quarterly updates and the final declaration go through compatible software. If you keep your records in a spreadsheet, you'll need bridging software to connect it to HMRC, because manual copy-paste between programs isn't allowed under the digital-links rule.
Second, the final declaration is still the moment of truth. Your quarterly updates are running totals of business figures only. Nothing is finalised, and no reliefs are claimed, until the final declaration.
What stays exactly the same?
It's reassuring to be clear about what isn't changing, because a lot of the noise around MTD makes it sound like a brand-new tax.
- The 31 January deadline. Your final declaration is due by 31 January following the end of the tax year, the same date your Self Assessment return was due.
- The payment dates. Your balancing payment is still due by 31 January, and payments on account (where they apply) are still due 31 January and 31 July.
- What's taxable. MTD changes how you report, not how rental or trading profit is calculated, nor the rates and allowances that apply.
- Other income still counts. Employment, pensions, dividends and savings interest are still declared and taxed, just at the final declaration rather than on a separate return.
For the underlying tax figures themselves, our Self Assessment service page and HMRC's rate guidance are the reference points. MTD doesn't rewrite the income tax bands.
How do quarterly updates and the final declaration fit together?
Think of the year as four light-touch updates followed by one proper sign-off.
A quarterly update is a cumulative, year-to-date summary of your business income and expenses by category, sent from your software. HMRC's guidance is specific on this: "Each quarterly update covers from the start of the tax year to the end of the update period, not just the previous three months." So your third update restates the whole year so far, not just months seven to nine. They are not four mini tax returns, and they don't finalise anything.
Each business reports separately. All your UK property is treated as one property business; UK and overseas property are separate businesses; and a sole-trade alongside a let property is another separate stream. So you might send more than one set of quarterly updates.
The standard quarterly periods and deadlines for 2026/27 are below. (You can elect for "calendar quarter" periods ending on the last day of the month instead, but the deadlines stay the same.)
| Quarter covers | Standard deadline |
|---|---|
| 6 April to 5 July | 7 August |
| 6 April to 5 October | 7 November |
| 6 April to 5 January | 7 February |
| 6 April to 5 April | 7 May (following tax year) |
Then, after the tax year ends, the final declaration pulls it all together: your finalised business figures, any accounting adjustments, all your other income, your reliefs and allowances, and your confirmation that it's correct. That generates your tax bill.
What do you actually report at the final declaration?
This is where the final declaration earns its "replaces the tax return" billing. It's not just a tick-box on top of your quarterly updates. According to HMRC's guidance, you add the income that wasn't in your quarterly updates, including:
- Employment (PAYE) income
- Income from state, private and occupational pensions
- Dividends (including from your own company)
- Savings interest
- Any other income normally reported through Self Assessment
You also make any final adjustments to your self-employment and property figures, then claim your reliefs and allowances. Only at this point is your tax for the year finalised.
A useful way to hold it in your head: the quarterly updates are about your business; the final declaration is about you, the whole taxpayer.
Illustrative example: a landlord's first MTD year
Illustrative example. Priya is a UK residential landlord with two let properties and a part-time PAYE job. Her gross rental income (before expenses) for 2024/25 was £58,000, which is over the £50,000 qualifying-income threshold, so she's mandated into MTD for Income Tax from 6 April 2026, the first day of the 2026/27 tax year.
Here's how her 2026/27 year runs:
- Her two properties are one UK property business, so she sends one set of quarterly updates, not two.
- Each quarter, her software sends HMRC a year-to-date summary of her rental income and expenses by 7 August 2026, 7 November 2026, 7 February 2027 and 7 May 2027.
- Her PAYE salary is not in those updates. It doesn't count toward the qualifying-income threshold either, because only self-employment and property income aggregate for that test. But it is still taxable.
- After 5 April 2027, she completes her final declaration, due 31 January 2028. Here she finalises the property figures, adds her PAYE salary and a small amount of savings interest, claims her allowances and her residential finance-cost relief, and confirms everything is correct.
- That final declaration generates her Self Assessment tax bill for 2026/27, payable by 31 January 2028.
The mechanics of the year change a lot. The destination, a finalised tax position by 31 January, doesn't.
If you're weighing up the wider landlord picture, our guidance for landlords walks through how MTD sits alongside the rest of your property tax obligations.
Your MTD deadline calendar
For a landlord or sole trader mandated from 6 April 2026, the 2026/27 cycle looks like this:
| Date | What's due |
|---|---|
| 7 August 2026 | Quarter 1 update (6 Apr to 5 Jul 2026) |
| 7 November 2026 | Quarter 2 update (year to 5 Oct 2026) |
| 7 February 2027 | Quarter 3 update (year to 5 Jan 2027) |
| 7 May 2027 | Quarter 4 update (full year to 5 Apr 2027) |
| 31 January 2028 | Final declaration and balancing payment for 2026/27 |
Note the overlap: by the time you finalise 2026/27, you'll already be a few quarters into your 2027/28 updates. That rolling rhythm is the biggest day-to-day change, and the main reason getting your bookkeeping in order early pays off.
Who has to do this, and from when?
MTD for Income Tax is being phased in by qualifying-income band. Qualifying income is your gross income (turnover before expenses) from self-employment and property, aggregated. Employment and pension income don't count toward the threshold, though they're still reported at the final declaration.
| Qualifying income over | Mandated from | Based on the return for |
|---|---|---|
| £50,000 | 6 April 2026 | 2024/25 |
| £30,000 | 6 April 2027 | 2025/26 |
| £20,000 | 6 April 2028 | 2026/27 |
If your qualifying income is below £20,000, you're not currently mandated, and you carry on with Self Assessment as normal until HMRC says otherwise. There's also an exemption route if you're digitally excluded.
What happens if you miss a deadline?
MTD for Income Tax brings in a points-based late-submission penalty system. In simple terms, you collect a penalty point each time you miss a submission deadline, and once you reach the threshold for your filing frequency, a £200 penalty applies, with a further £200 for each later miss while you're at the threshold. Late-payment penalties are separate and are based on how late the payment is, not on points.
HMRC has also confirmed it won't charge penalties for late quarterly updates in the first year for those mandated from April 2026, to give people time to adjust. The figures and exact thresholds are set out on HMRC's penalties guidance, linked in Sources below, and we'd point you there rather than rely on memory, because this is still bedding in.
If the rolling deadlines feel like a lot to manage on top of running a business, that's exactly the kind of thing we take off your plate. Our Self Assessment and MTD support covers digital record-keeping, quarterly updates and your final declaration end to end. Book a call with a Zmartly accountant to get your MTD setup sorted before your first quarter is due.
Frequently asked questions
Does the final declaration replace my Self Assessment tax return?
Yes. For people in MTD for Income Tax, the final declaration replaces the Self Assessment return. It's where you finalise your business figures, add your other income, claim reliefs and allowances, and confirm everything is correct. The information generates your Self Assessment tax bill for the year.
When is the final declaration due?
By 31 January following the end of the tax year, the same deadline as the old Self Assessment return. For the 2026/27 tax year, that's 31 January 2028. You can submit earlier if you're ready.
Do quarterly updates replace my tax return?
No. Quarterly updates are cumulative year-to-date summaries of your business income and expenses only. They don't claim reliefs and don't finalise your tax. The final declaration does that job after the year ends.
Do I still pay my tax on 31 January?
Yes. Your balancing payment for the year is still due by 31 January, and payments on account (where they apply) are still due 31 January and 31 July. MTD changes the reporting, not the payment dates.
Does my employment or pension income go in the quarterly updates?
No. Quarterly updates cover only your self-employment and property income. Employment, pensions, dividends and savings interest are added at the final declaration, where your full tax position is finalised.
Can I still use a spreadsheet?
You can keep records in a spreadsheet, but you'll need bridging software to send your updates and final declaration to HMRC, because MTD requires digital records with digital links and doesn't allow manual copy-paste between programs.
