What Actually Changes at Year End Under MTD

If you've got your head around sending four quarterly updates, the year-end step can feel like a mystery. You've been keeping digital records and ticking off those cumulative totals every three months. Then April comes, the tax year closes, and there's one more thing to do: the tax return.

This is the part where everything comes together. It's also the part that worries landlords most, usually because they assume it's going to be a huge separate job. It isn't. Let me walk you through what actually changes.

Your four updates were a running total, not the final word

From 2025-26 onwards, quarterly updates are cumulative. Each one shows your income and expenses for the tax year so far, not just that one quarter. So by the time you send your fourth update in early May, HMRC already has a year-to-date picture of your rental figures.

But those updates are deliberately rough. They're your income and expenses as you recorded them through the year. They don't include the allowances, reliefs and adjustments that turn a pile of figures into an actual tax position. That final shaping happens at year end.

Think of the quarterly updates as your working shown in pencil. The tax return is where it gets confirmed and signed off.

What the tax return is (and what it replaces)

The year-end step is called the tax return (HMRC previously called this the final declaration). It's due by 31 January following the end of the tax year, the exact same deadline Self Assessment always used. For the 2026-27 tax year, that means 31 January 2028.

For the income that's inside MTD, your four quarterly updates plus this one tax return replace the old Self Assessment process entirely. You're not doing both. You can read more in our guide to the MTD tax return and what replaces Self Assessment, but the short version is: the return is where you confirm the year's figures and add everything the quarterly updates left out.

The adjustments that only happen at year end

Here's what typically gets added or sorted out when you file the return:

• The property income allowance (£1,000 tax-free). This is an alternative to deducting your actual expenses, not something you claim on top. If your real expenses are higher, you'd claim those instead.
• Rent-a-room relief, up to £7,500 a year tax-free if you let a furnished room in your own home (not a whole-property let). More on that in the GOV.UK rent-a-room guidance.
• Your personal allowance and the correct tax bands applied across all your income.
• Private use adjustments, for example if part of a cost wasn't wholly for the rental.
• Any other income you have outside MTD, such as employment, pensions or savings interest, which still needs declaring here.
• Finance cost relief on mortgage interest, given as a basic-rate tax reduction rather than a straight expense.

None of this needs to appear in your quarterly updates. It all lands at year end, which is exactly why the return exists.

A worked example

Oliver lets out one flat. Across his four quarterly updates for 2026-27, he reported gross rent of £14,400 and expenses of £3,200, including letting agent fees, repairs and his buildings insurance.

Those updates showed a running profit of £11,200. But they didn't tell the full story.

At year end, Oliver sits down with his tax return. His mortgage interest for the year came to £4,800. Under the current rules this isn't deducted as an expense, so it stays out of that £11,200 figure. Instead it gives him a basic-rate tax reduction. That reduction is 20% of £4,800 (£960) in principle — but it's capped at the lowest of 20% of the finance costs, 20% of his property profits, or 20% of his income above the personal allowance, so the actual figure can be lower. Because Oliver also has part-time employment income that uses up his personal allowance, and property profits comfortably above £4,800, the full £960 is defensible here.

Since Oliver is claiming £3,200 of actual expenses, he wouldn't also use the £1,000 property income allowance — it's one or the other, and the actual expenses are the better deal.

He also realises one "repair" he logged was partly an improvement, so he adjusts it. Then his personal allowance and tax bands get applied across his rental profit and his employment income together.

The quarterly updates did most of the legwork; the return is where the allowances and reliefs are applied and the actual tax bill is settled. (The proportions here are just to illustrate the point, not fixed amounts.) The figures came straight from the records he'd been keeping all year, so there was nothing to dig out from scratch.

When the deadline actually bites

Missing a quarterly update earns a penalty point, not an immediate fine, as explained in the MTD penalties guidance. The 31 January tax return deadline is different. This is the date your tax is due to be paid, so late payment carries interest and late-payment penalties in the usual Self Assessment way. You can see the detail on GOV.UK's Self Assessment penalties page.

So the year-end return is the deadline to take seriously. The good news is you've got from 6 April right through to the following 31 January to do it.

Why doing it properly all year makes this painless

The landlords who find year end stressful are usually the ones scrambling to reconstruct a year of figures in January. The ones who kept clean digital records as they went just open their software, check the adjustments, and file.

Quarterwise keeps your records tidy through the year and files both your quarterly updates and your tax return to HMRC, so year end becomes a quick review of figures you already trust. Get the records right during the year, and year end is just the sensible full stop at the end of it.

This is general information, not tax advice. Please check your own position with HMRC or a qualified accountant.