Key UK Tax Dates and Deadlines for the 2026/27 Tax Year

Missing a UK tax deadline is one of the most avoidable, and most expensive, mistakes a taxpayer can make. Penalties and interest accrue automatically, and they apply whether you live in London, Dubai, Singapore or Hong Kong. This is a practical calendar of the dates that matter for the 2026/27 tax year, followed by a short FAQ and the HMRC links you are most likely to need.

The 2026/27 tax year runs from 6 April 2026 to 5 April 2027. Most of the filing and payment deadlines that fall during this period actually relate to the 2025/26 tax year, which ended on 5 April 2026. That overlap is the single biggest source of confusion, so we have set out clearly which year each deadline belongs to.

The Tax Year at a Glance

| Date | What happens | |---|---| | 6 April 2026 | 2026/27 tax year begins | | 31 May 2026 | Employers must give employees their P60 for 2025/26 | | 6 July 2026 | Deadline to file P11D and P11D(b) forms for 2025/26, and to give employees a copy | | 22 July 2026 | Deadline to pay Class 1A National Insurance on benefits for 2025/26 (electronic payment) | | 5 October 2026 | Deadline to register for Self Assessment if you have a new filing obligation for 2025/26 | | 31 October 2026 | Deadline to file a paper Self Assessment return for 2025/26 | | 30 December 2026 | Deadline to file online if you want HMRC to collect tax owed (under £3,000) through your 2027/28 PAYE code | | 31 January 2027 | Deadline to file your online Self Assessment return for 2025/26, pay the balancing payment for 2025/26, and pay the first payment on account for 2026/27 | | 5 April 2027 | 2026/27 tax year ends | | 31 July 2027 | Deadline to pay the second payment on account for 2026/27 |

Two further deadlines do not sit neatly in a calendar because they depend on your own transactions:

• PAYE monthly payments. If you operate a payroll, PAYE and National Insurance are due by the 19th of the following month if you pay by post, or the 22nd if you pay electronically.
• Capital gains tax on UK residential property. Any reportable gain must be declared and the tax paid within 60 days of completion. This applies to UK residents with a chargeable gain, and to non-UK residents on any UK property disposal, even where no tax is due. We cover this in detail in our separate note on the 60-day deadline.

Self Assessment: The Deadlines That Catch People Out

For most of our clients, Self Assessment is the part of the calendar that matters most. Three points are worth highlighting.

Registering in time. If 2025/26 is the first year you need to file, perhaps because you have started letting a UK property, become self-employed, or received untaxed foreign or investment income, you must tell HMRC by 5 October 2026. Register late and you can face a "failure to notify" penalty on top of any tax due.

Paper versus online. The paper deadline (31 October 2026) is three months earlier than the online deadline (31 January 2027). The overwhelming majority of expatriate returns are filed online, but if you intend to file on paper, you have far less time.

Two payments, not one. The 31 January 2027 deadline is both a filing deadline and a payment deadline. You pay any balancing payment for 2025/26 and, if your liability is high enough, your first payment on account for 2026/27 on the same day. The second payment on account follows on 31 July 2027. Many people budget for the tax bill but forget the payment on account, which can be up to 50% of the previous year's liability on top.

Deadline FAQ

What is a payment on account? It is an advance payment towards your next year's tax bill, made in two instalments (31 January and 31 July). Each instalment is normally half of your previous year's liability. Payments on account are not required if your last Self Assessment bill was under £1,000, or if more than 80% of your tax was collected at source (for example through PAYE).

What if I file or pay late? For a late return, HMRC charges an automatic £100 penalty as soon as the deadline passes, even if you owe no tax or are due a refund. After three months, daily penalties of £10 per day can apply (up to £900), with further penalties at six and twelve months. Late payment attracts separate penalties, plus interest charged daily from the due date until you pay. The figures above should be confirmed against current HMRC guidance, as penalty and interest rates are reviewed regularly.

I have left the UK. Do these deadlines still apply to me? Very possibly, yes. Non-residents still have UK filing obligations on UK rental income, UK property disposals, and certain other UK-source income. Leaving the UK does not switch off the Self Assessment calendar, and the 60-day CGT rule applies to non-residents on all UK property disposals.

Can I just have the tax taken out of my salary or pension? If you file online by 30 December 2026 and owe less than £3,000, you can usually ask HMRC to collect the amount through your tax code rather than as a lump sum. This option is not available to everyone, and it is not available at all if you miss the 30 December date.

Which tax year am I actually filing for? The return due on 31 January 2027 covers the 2025/26 tax year (6 April 2025 to 5 April 2026). You are always filing for the year that has just ended, not the one you are currently in.

Useful HMRC Links

These are the official gov.uk pages we point clients to most often. Always rely on the gov.uk source rather than third-party summaries, as guidance is updated frequently.

• Self Assessment tax returns - overview, who must file, and how to register: gov.uk/self-assessment-tax-returns
• How to pay your Self Assessment tax bill - payment methods, bank details, and timing: gov.uk/pay-self-assessment-tax-bill
• National Insurance - classes, rates, and voluntary contributions: gov.uk/national-insurance
• Sign in to your HMRC online account - file returns, check what you owe, and view your tax record: gov.uk/log-in-register-hmrc-online-services
• Your personal tax account - a single place to manage your personal tax online: gov.uk/personal-tax-account
• Contact HMRC - phone, post, and webchat for general enquiries: gov.uk/government/organisations/hm-revenue-customs/contact

How We Can Help

We manage the full Self Assessment calendar for clients across multiple time zones, so deadlines are met without you having to track them yourself. That includes registering you for Self Assessment, preparing and filing your return, calculating payments on account, and handling 60-day CGT property reports. If you are unsure which of these dates apply to your situation, please get in touch and we will map your personal deadline calendar for the year.