Goodbye Self Assessment: Meet Your Final Declaration

If you've filed a Self Assessment tax return before, you'll know the drill: once a year you gather everything together, tot it up, and send HMRC one big summary of your income and tax. For decades, that single annual return has been how landlords tell the taxman what they earned.

Making Tax Digital for Income Tax changes how you get there — but the final destination is reassuringly familiar. That destination is called the final declaration, and it's essentially your new Self Assessment return. Let's walk through what it is and why it's genuinely nothing to lose sleep over.

First, a quick reminder of where this fits

Making Tax Digital for Income Tax (MTD for Income Tax, or MTD ITSA) applies to landlords and the self-employed. It's being phased in based on your qualifying income — that's your gross rental and self-employment income before you take off any expenses.

The timeline looks like this:

Over £50,000: from 6 April 2026
Over £30,000: from 6 April 2027
Over £20,000: from 6 April 2028

If your qualifying income is under £20,000, you're not required to join yet.

Once you're in MTD, there are three things you do:

Keep digital records of your income and expenses.
Send HMRC four quarterly updates each tax year.
Submit one final declaration after the tax year ends.

It's that third step we're focusing on today.

So what exactly is the final declaration?

Think of your four quarterly updates as rough running totals during the year. They're cumulative — each one builds on the last to show your year-to-date income and expenses. They're handy for keeping you on track, but they aren't the full, polished picture.

The final declaration is where that picture gets finished. It's the moment you tell HMRC, "Right, that's my complete and final position for the year — this is everything."

At this stage you confirm your rental figures are correct and add anything that wasn't captured in your quarterly updates. That might include:

Any reliefs or allowances you're claiming
Other sources of income (such as employment, savings or dividends)
Adjustments or final tweaks to your figures

Once you've confirmed it all, HMRC works out the tax you owe, just as it always did. In other words, the final declaration does the job your old Self Assessment return used to do — it's simply the new name and the new route.

When is it due?

Here's the part that should feel comfortingly familiar: the final declaration is due by 31 January following the end of the tax year.

That's the exact same date you've always known for Self Assessment. The UK tax year runs from 6 April to 5 April, so for any given year you'll have until the following 31 January to finalise and submit.

So while the quarterly updates are new (with their own deadlines through the year), the big annual deadline hasn't moved. One less thing to relearn.

Why this is easier than it sounds

If the idea of an extra submission makes you nervous, here's the reassuring truth: by the time you reach your final declaration, most of the work is already done.

Under the old system, January was often a mad scramble — digging out bank statements, hunting for receipts, trying to remember what that payment in June was for. With MTD, you've been keeping digital records and sending quarterly updates all year long. The figures are already there.

That means the final declaration becomes a review-and-confirm exercise rather than a from-scratch panic. You're checking work you've already done, adding any last details, and pressing submit.

Think of it like this: instead of cooking the whole meal on the night, you've been prepping all week. The final step is just plating up.

You really can do this yourself

Plenty of landlords with one property or a small portfolio worry they'll now need an accountant. For many, that simply isn't the case. If your tax affairs are straightforward, MTD is designed to be manageable on your own — especially with software that keeps your records tidy and files for you.

This is exactly what Quarterwise is built for. It keeps your digital records as you go, files your quarterly updates, and helps you submit your final declaration to HMRC — so the year-end becomes a calm tidy-up rather than a cliff edge.

The final declaration isn't a new burden. It's the same end goal you've always met, reached by a steadier, less stressful path.

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