UK Tax Deadlines 2026/27: Every Date and What Missing It Costs

The tax return you file by 31 January 2027 covers money you earned as far back as 6 April 2025, and the payment you make that day usually includes an advance on the tax year you're living in now. Two tax years are always running at once, which is why the dates feel arbitrary. Here is every UK tax deadline on one timeline, showing which tax year each one belongs to and what missing it costs.

Last updated: 12 August 2026

Two tax years are running at the same time

The UK tax year runs from 6 April to 5 April. That part is straightforward. The part that catches people out is that a tax year doesn't finish when it ends. The 2025/26 tax year stopped counting income on 5 April 2026, but you don't have to report it until 31 January 2027, you don't have to pay the balance until the same day, and you can still amend the return until 31 January 2028. For almost all of that stretch you're also earning inside 2026/27.

So at any moment there are two tax years in play: the one you're living in, and the one you're settling up for. Every deadline below belongs to one or the other. The diagram shows which.

As for why the year starts on such an odd date, that's a leftover from 1752. Britain moved from the Julian to the Gregorian calendar and dropped 11 days to catch up. The tax year had always started on Lady Day, 25 March, and the Treasury had no intention of losing 11 days of revenue, so it moved the year-end instead. One more day was added in 1800 over a leap year the two calendars disagreed about, which landed the start on 6 April. Nothing has shifted it since.

How to read this

2025/26 tax year
2026/27 tax year

A solid bar means you're earning inside that tax year. A striped bar means the year has ended and you're reporting and paying it. Where both rails are filled, two tax years are running at once.

6 April 2025

2025/26 tax year starts

Allowances, tax bands and the ISA limit all reset.
31 January 2026 Self Assessment

First payment on account for 2025/26

Paid two months before the year it covers has even ended, worked out as half your 2024/25 bill.
5 April 2026

2025/26 tax year ends

Last day to use the 2025/26 ISA allowance, pension annual allowance and £3,000 capital gains exemption. None of it carries over.
6 April 2026

2026/27 tax year starts

2025/26 is closed and the clock starts on reporting it. Making Tax Digital for Income Tax also begins for sole traders and landlords with qualifying income over £50,000.
31 May 2026 Employed

P60 for 2025/26

Your employer must give you a P60 showing your 2025/26 pay and tax.
6 July 2026 Employed

P11D for 2025/26

Employers report taxable benefits like a company car or medical cover. The Class 1A National Insurance on them is due by 22 July.
31 July 2026 Self Assessment

Second payment on account for 2025/26

The other half of your 2024/25 bill, paid in advance against 2025/26.
7 August 2026 Making Tax Digital

First quarterly update

Covers 6 April to 5 July 2026, the first quarter of the 2026/27 tax year.
5 October 2026 Self Assessment

Register for Self Assessment for 2025/26

Tell HMRC if you had untaxed income in 2025/26 and don't already file a return.
31 October 2026 Self Assessment

Paper tax return for 2025/26

Only if you file on paper. Online filers get three more months.
7 November 2026 Making Tax Digital

Second quarterly update

Covers 6 April to 5 October 2026.
30 December 2026 Self Assessment

File 2025/26 online to pay through your tax code

Owe under £3,000 and have PAYE income? File by this date and HMRC spreads it across your 2027/28 tax code instead of taking it in one go.
31 January 2027 Self Assessment

Four deadlines land on one day

The 2025/26 online return, the 2025/26 balancing payment, the first payment on account for 2026/27, and the last day to amend your 2024/25 return.
7 February 2027 Making Tax Digital

Third quarterly update

Covers 6 April 2026 to 5 January 2027.
5 April 2027

2026/27 tax year ends

Last day for the 2026/27 ISA allowance, and the last day to claim a tax refund for 2022/23.
6 April 2027

2027/28 starts, 2026/27 reporting begins

The same cycle again, one year along.
7 May 2027 Making Tax Digital

Fourth quarterly update

Covers the whole of 2026/27.
31 January 2028 Self Assessment

2026/27 return and payment

Where the 2026/27 tax year finally closes, 22 months after it opened.

Every UK personal tax deadline from the first day of the 2025/26 tax year to the day its successor is finally paid off. Dates are for the 2025/26 and 2026/27 tax years and shift by a year each April.

The deadline that isn't on the diagram

Capital Gains Tax on UK residential property: 60 days from completion

Sell a second home, a buy-to-let or any UK residential property at a gain and you have 60 days from the completion date to report it and pay the tax. Not 31 January. Not with your tax return. 60 days, through a Capital Gains Tax on UK property account, and the tax has to be paid inside that window too.

It can't be drawn on a calendar because it runs from your completion date, so it falls on a different day for every seller. If you also file Self Assessment, the disposal still goes on the return afterwards. Gains on shares, funds and crypto are different: those wait for the return and the normal 31 January deadline.

Try the calculator

Take-home Pay Calculator

Check what you should be paying across the 2026/27 tax year before a deadline tells you. Works for Scotland and the rest of the UK.

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What each deadline costs if you miss it

gov.uk states every one of these rules correctly, then stops before telling you the price. The price is the useful bit, and it varies more than you'd think: some of these deadlines cost nothing at all to miss, and one of them costs £100 before HMRC has even looked at whether you owe anything.

Date	Deadline	Cost of missing it
31 Jul 2026	Second payment on account for 2025/26	Interest at 7.75% from 1 August. No penalty: the 5% charges don't apply to payments on account.
5 Oct 2026	Register for Self Assessment	A percentage of the tax you should have declared, up to 30% where the failure wasn't deliberate. Tell HMRC before they ask and it can come down to nothing.
31 Oct 2026	Paper tax return	Nothing, as long as you switch to filing online by 31 January. Send paper after 31 October and it's £100.
30 Dec 2026	File online to pay through your tax code	No penalty. You lose the option to spread the bill, so all of it falls due on 31 January.
31 Jan 2027	Online tax return for 2025/26	£100 immediately, even if your bill is zero. Then the ladder below.
31 Jan 2027	Balancing payment for 2025/26	Interest at 7.75% from 1 February, then 5% of whatever is still unpaid at 30 days, 6 months and 12 months.
60 days	CGT on a UK residential property sale	£100, rising with further penalties the longer it runs, plus interest on the unpaid tax.

Deadlines shown for the 2025/26 tax year. 2026/27 follows the same pattern one year later.

Filing late: the penalty ladder

The £100 is automatic and it isn't linked to what you owe. Someone with a nil return who files on 1 February pays exactly the same £100 as someone with a £40,000 bill. After that the charges stack rather than replace each other.

How late	Charge	Running total
1 day	£100 fixed	£100
3 months	£10 a day for up to 90 days	up to £1,000
6 months	5% of the tax due, or £300 if that's more	£1,300
12 months	another 5%, or £300 if that's more	£1,600

Running totals assume the £300 minimums apply, which they do on any bill up to £6,000. Above that the 5% charges are larger and the total grows with the tax. None of this includes the tax itself, or the separate charges for paying late.

Paying late: interest first, then penalties

Interest starts the day after the deadline and runs until you pay. HMRC sets it at the Bank of England base rate plus 4 percentage points, which since 9 January 2026 has meant 7.75%. That margin used to be 2.5 points and was widened in April 2025, so late payment now costs noticeably more than it did.

On top of the interest, 5% of the tax still outstanding is charged at 30 days, again at 6 months, and again at 12 months. Those 5% charges apply to the balancing payment. A late payment on account attracts interest only, which is a real distinction if cash is tight in July: paying the July instalment a month late is a much smaller problem than paying the January one a month late.

If you know you can't pay, a Time to Pay arrangement set up before the deadline stops the penalties. Interest still runs.

Why 31 January is four deadlines, not one

This is where the two-year lag does the most damage, because a single date carries obligations from three different tax years:

The 2025/26 return. Income earned between 6 April 2025 and 5 April 2026.
The 2025/26 balancing payment. Whatever that return says you owe, less the two payments on account you already made in January and July 2026.
The first payment on account for 2026/27. Half of the 2025/26 bill again, paid in advance on a year that still has two months left to run.
The last chance to amend 2024/25. You get 12 months from a filing deadline to change that return, and this is the day it shuts.

The third one is what makes January bills feel so much larger than expected. If your income has grown, you're settling last year's shortfall and pre-paying half of this year's larger bill on the same day. Payments on account are skipped only if last year's bill came to under £1,000, or if more than 80% of your tax was already collected at source through a tax code or by your bank.

The dates that aren't on your calendar

Making Tax Digital started on 6 April 2026

This is the biggest change to personal tax deadlines in years and it went live at the start of the current tax year. If you're a sole trader or landlord and your qualifying income was over £50,000 in 2024/25, you're in Making Tax Digital for Income Tax now. HMRC writes to confirm it, so you shouldn't have to work it out yourself.

Being in it means four quarterly updates a year on top of the tax return. The updates are cumulative and they don't replace anything: 31 January is still 31 January.

Period covered	Calendar-quarter option	Due
6 Apr to 5 Jul	1 Apr to 30 Jun	7 August
6 Apr to 5 Oct	1 Apr to 30 Sep	7 November
6 Apr to 5 Jan	1 Apr to 31 Dec	7 February
6 Apr to 5 Apr	1 Apr to 31 Mar	7 May

The thresholds step down from here. Qualifying income over £30,000 in 2025/26 brings you in from 6 April 2027, and over £20,000 in 2026/27 brings you in from 6 April 2028.

Joining also moves you onto a different penalty regime. Late updates are points-based: one point per missed deadline, £200 once you hit four points, and £200 for every miss after that. HMRC isn't issuing points for late quarterly updates during 2026/27, so this year is a free run. Late payment is stricter than standard Self Assessment, charging 3% at day 15 and another 3% at day 30, then 10% a year accruing daily from day 31. Those first two charges are waived in 2026/27 and rise to 4% each from 2027/28.

5 April: what disappears at midnight

Four allowances reset on 5 April and three of them vanish entirely if you haven't used them.

ISA allowance, £20,000. Gone at midnight, with no carry-forward. The ISA allowance guide covers how it splits across account types.
Capital gains exemption, £3,000. Also gone, which is why selling investments across two tax years can be worth planning.
Dividend allowance, £500. No carry-forward.
Pension annual allowance, £60,000. The exception. Unused allowance carries forward, but only 3 years, so whatever you didn't use in 2023/24 is gone after 5 April 2027.

Looking backwards: the four-year window

Deadlines run in the other direction too. You have 4 years from the end of a tax year to claim back tax you overpaid, which means that during 2026/27 you can still go back to 2022/23, and that door closes on 5 April 2027. If you've ever been on an emergency code or had a wrong tax code, that's the window you're working inside. Marriage Allowance backdates on the same 4 years.

Voluntary National Insurance is a longer window and a different one: 6 years, cutting off on 5 April each year. The temporary extension that let people fill gaps back to 2006 ended on 5 April 2025 and hasn't returned.

If you're in Scotland

Scottish income tax is set at Holyrood but collected through the same HMRC system with an S-prefix tax code, so every date above applies unchanged. 31 January, 31 July and 5 October are the same in Aberdeen as in Bristol.

Two deadlines are Scotland-only, and both belong to Revenue Scotland rather than HMRC. Buy a property and the LBTT return is due within 30 days of the day after the effective date, on any transaction of £40,000 or more, even when there's no tax to pay. And if you paid the Additional Dwelling Supplement because you bought before selling, you have 36 months to sell the old home and reclaim it. Our LBTT guide goes through both.

Whichever side of the border you're on, the fastest way to know whether a January bill is coming is to check what you should be paying now. The Take-home Pay Calculator does that for the 2026/27 tax year.

Frequently asked questions

When is the Self Assessment deadline?

11:59pm on 31 January 2027 for the 2025/26 tax year, if you file online. Paper returns were due by 31 October 2026. The same 31 January date is the deadline to pay what you owe, and missing it by a single day costs £100 even if your bill is zero.

What tax year does the 31 January 2027 deadline cover?

2025/26, which ran from 6 April 2025 to 5 April 2026. That's why the deadline feels so far behind: you're reporting income you earned up to 22 months earlier. The same payment usually also includes the first payment on account for 2026/27, the year you're in now.

What happens if I miss the Self Assessment deadline?

You get an automatic £100 penalty straight away, whether or not you owe any tax. After 3 months it becomes £10 a day up to £900, at 6 months a further 5% of the tax or £300, and at 12 months another 5% or £300. Paying late is charged separately at 5% of the unpaid tax at 30 days, 6 months and 12 months, with interest at 7.75% running throughout.

When does the UK tax year end?

5 April, with the new one starting 6 April. Anything you want counted for a tax year has to happen by 5 April: your ISA allowance, your pension annual allowance and your £3,000 capital gains exemption all reset that night, and none of them carry over.

How long do I have to report Capital Gains Tax on a property sale?

60 days from completion, and you have to pay the tax inside that window too rather than waiting for your tax return. It applies to UK residential property where there's a gain to report, and it runs from your own completion date, so it lands on a different day for everyone. Miss it and you get a penalty plus interest.

Do Scottish taxpayers have different tax deadlines?

No. Scottish income tax runs through the same HMRC system with an S-prefix tax code, so 31 January, 31 July and 5 October all apply exactly as they do in the rest of the UK. Scotland adds two of its own for property: an LBTT return within 30 days of buying, and 36 months to reclaim the Additional Dwelling Supplement.