When Does the Tax Year Start and End? Your 2026/27 Guide to Key Dates and Deadlines

The UK tax year runs from 6 April to 5 April the following year. That much is simple. But the cascade of deadlines that flow from those dates – for Self Assessment, corporation tax, PAYE, VAT, and more – is where most people lose track.

Missing a deadline doesn’t just mean a penalty. It can mean interest charges, HMRC enquiries, and unnecessary stress. Knowing what’s due and when gives you time to plan, and planning is what keeps tax bills manageable.

Here’s a full walkthrough of how the tax year works, every deadline that matters for 2026/27, and what’s changed this year.

Why Does the Tax Year Start on 6 April?

It’s a question everyone asks, and the answer goes back to 1752. Before that year, the calendar year began on 25 March (Lady Day) and the tax year ran alongside it.

When Britain switched from the Julian to the Gregorian calendar, 11 days were dropped to align with the rest of Europe. To make sure the Treasury didn’t lose 11 days’ worth of tax revenue, the tax year end was pushed forward – eventually landing on 5 April, where it’s stayed ever since.

It’s quirky, it’s outdated, and it’s not changing any time soon.

The Key Dates for 2026/27

The 2026/27 tax year runs from 6 April 2026 to 5 April 2027. Here are the deadlines you need in your diary, broken down by tax type.

Self Assessment

If you file a Self Assessment return – whether you’re self-employed, a company director, a landlord, or a higher earner – these are the dates that matter for the 2025/26 tax year (the return you’re filing during 2026/27):

• 5 October 2026: deadline to register for Self Assessment if you need to file for the first time for 2025/26
• 31 October 2026: deadline for paper Self Assessment returns
• 30 December 2026: deadline to file online if you want HMRC to collect underpaid tax (up to £3,000) through your PAYE code
• 31 January 2027: deadline for online Self Assessment returns and for paying any tax owed for 2025/26. Also the deadline for your first payment on account for 2026/27
• 31 July 2027: second payment on account for 2026/27

The 31 January deadline is the one that catches the most people. It’s both a filing and a payment deadline, and missing it triggers an automatic £100 penalty for late filing, plus interest on any unpaid tax.

Corporation Tax

Corporation tax deadlines are tied to your company’s accounting period, not the tax year. But if your company follows a standard 31 March year end, the deadlines for the period ending 31 March 2026 are:

• 1 January 2027: corporation tax payment due (nine months and one day after year end)
• 31 March 2027: CT600 return filing deadline (twelve months after year end)

Remember – the payment comes before the filing deadline. Many directors get caught assuming they’re the same date.

From 1 April 2026, all company tax returns must be filed using commercial software. HMRC’s old online filing service has closed. And late filing penalties have doubled – the basic penalty is now £200, rising to £1,000 for repeat offenders.

Payroll (PAYE)

If you employ staff, payroll deadlines run throughout the year:

• On or before each payday: submit your Full Payment Submission (FPS) to HMRC via Real Time Information
• 19 April 2026: deadline to file your final FPS or Employer Payment Summary (EPS) for 2025/26
• 19th/22nd of each month: PAYE and NIC payment due to HMRC (19th for postal payments, 22nd for electronic)
• 31 May 2026: deadline to issue P60s to all employees who were on your payroll on 5 April 2026
• 6 July 2026: deadline to file P11D and P11D(b) forms for benefits in kind
• 22 July 2026: deadline to pay Class 1A National Insurance on benefits reported

VAT

VAT deadlines depend on your filing frequency and your VAT period dates, but for quarterly filers, the standard pattern is:

• VAT return and payment due: one month and seven days after the end of the VAT quarter

So a quarter ending 30 June 2026 would have a return and payment deadline of 7 August 2026. Under Making Tax Digital for VAT, returns must be submitted through compatible software – there’s no option to file manually.

Capital Gains Tax (Property)

If you sell a residential property that isn’t your main home during the 2026/27 tax year:

• Within 60 days of completion: report the disposal and pay the CGT owed via HMRC’s online service
• 31 January 2028: include the disposal on your Self Assessment return for 2026/27

The 60-day rule applies even if you already file Self Assessment. It’s a separate, earlier deadline.

How the Tax Year Affects Businesses

For limited companies, the tax year itself is less directly relevant – your obligations are tied to your accounting period, which can end on any date you choose. But several things still align with the April-to-April cycle.

Payroll resets on 6 April each year – new tax codes take effect, NIC thresholds update, and year-end submissions become due. If you provide employee benefits, the P11D cycle follows the tax year.

And if you or your employees have Self Assessment obligations, the filing and payment deadlines are all anchored to the 31 January and 31 July milestones.

For sole traders and partnerships, the tax year is everything. Your profits for the period 6 April to 5 April form the basis of your Self Assessment return, and all your deadlines flow from it.

How Double Point Can Help

Keeping track of tax deadlines across Self Assessment, corporation tax, PAYE, VAT, and benefits reporting is a lot for any business owner to manage alone. Miss one, and the penalties start stacking up.

At Double Point, we manage the full compliance calendar for our clients – filing returns on time, scheduling payments, and flagging upcoming deadlines well in advance.

Whether you need help with your company accounts, personal tax return, or payroll year-end, we’re here to make sure nothing slips through the cracks.

Book a free consultation with us today and let’s get your tax calendar under control.