Missing a tax deadline is one of the most avoidable mistakes a business can make. The penalties are automatic, the interest charges add up quickly, and the stress is entirely unnecessary. Yet every year, thousands of businesses across Northern Ireland get caught out.
This guide covers every key deadline for the 2026/27 tax year (6 April 2026 to 5 April 2027), along with some that carry over from earlier periods. Bookmark it, add the dates to your calendar, and refer back to it throughout the year.
The full 2026/27 tax calendar
April 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 6 April | Start of 2026/27 tax year | All businesses and individuals |
| 19 April | PAYE and NIC payment for month 12 (2025/26) | Employers (monthly schemes) |
| 22 April | Electronic PAYE payment deadline for month 12 | Employers paying electronically |
| 30 April | Deadline to file P46(car) for Q4 (Jan-Mar) | Employers providing company cars |
May 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 3 May | Singled-out for this year: this is the last day to submit 2024/25 Self Assessment without incurring further daily penalties | Late filers |
| 19 May | PAYE and NIC payment for month 1 (2026/27) | Employers (monthly schemes) |
| 31 May | P60s must be issued to all employees for 2025/26 | All employers |
Don’t overlook the P60 deadline. Every employee on your payroll at 5 April must receive their P60 by 31 May. It’s a legal requirement and employees need it for their own tax returns, mortgage applications, and benefit claims.
June 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 19 June | PAYE and NIC payment for month 2 | Employers (monthly schemes) |
July 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 6 July | P11D and P11D(b) filing deadline for 2025/26 | Employers providing benefits in kind |
| 6 July | Class 1A NIC due on benefits in kind | Employers |
| 19 July | PAYE and NIC payment for month 3 | Employers (monthly schemes) |
| 22 July | Electronic payment deadline for Class 1A NIC | Employers paying electronically |
| 31 July | Second payment on account for 2025/26 Self Assessment | Self-employed and directors |
Payments on account catch people out. If you filed your 2024/25 Self Assessment showing tax owed of more than £1,000, you’ll be making payments on account. The second instalment for 2025/26 was due 31 July 2026, and the next one falls on 31 January 2027 alongside your balancing payment. That January date is the one that stings, because it is two bills in one. Budget for it now rather than in the week before.
August to September 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 19 August | PAYE/NIC month 4 | Employers |
| 19 September | PAYE/NIC month 5 | Employers |
October 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 5 October | Register for Self Assessment if newly self-employed in 2025/26 | New sole traders, new directors with untaxed income |
| 19 October | PAYE/NIC month 6 | Employers |
| 31 October | Paper Self Assessment return deadline for 2025/26 | Those filing on paper (rare, but still allowed) |
November to December 2026
| Date | Deadline | Who it affects |
|---|---|---|
| 19 November | PAYE/NIC month 7 | Employers |
| 19 December | PAYE/NIC month 8 | Employers |
January 2027
| Date | Deadline | Who it affects |
|---|---|---|
| 19 January | PAYE/NIC month 9 | Employers |
| 31 January | Self Assessment return deadline for 2025/26 | All Self Assessment taxpayers |
| 31 January | Balancing payment for 2025/26 tax year | Self Assessment taxpayers |
| 31 January | First payment on account for 2026/27 | Self Assessment taxpayers |
31 January is the single most important date in the tax calendar. Three things are due at once: your return, your balancing payment, and your first payment on account for the following year. Do not leave this to the last week of January.
February to March 2027
| Date | Deadline | Who it affects |
|---|---|---|
| 19 February | PAYE/NIC month 10 | Employers |
| 19 March | PAYE/NIC month 11 | Employers |
Corporation tax deadlines
Corporation tax doesn’t follow the standard tax year. Instead, deadlines are based on your company’s accounting period (its financial year-end). Here’s how it works:
| Event | Deadline |
|---|---|
| Corporation tax payment | 9 months and 1 day after the end of the accounting period |
| Corporation tax return (CT600) | 12 months after the end of the accounting period |
| Amended return | 12 months from the original filing deadline |
Example: If your company year-end is 31 March 2027, your corporation tax is due by 1 January 2028, and the return must be filed by 31 March 2028.
For large companies (profits over £1.5 million), payments are due in quarterly instalments starting in the seventh month of the accounting period.
VAT deadlines
VAT-registered businesses must file returns and make payments on a regular cycle. The most common is quarterly.
| Scheme | Filing and payment deadline |
|---|---|
| Standard quarterly | 1 month and 7 days after the end of the VAT quarter |
| Monthly returns | 1 month and 7 days after the end of each month |
| Annual Accounting Scheme | 2 months after the end of the annual period |
If your VAT quarter ends on 30 June, your return and payment are due by 7 August.
Making Tax Digital (MTD) for VAT is mandatory for all VAT-registered businesses. You must keep digital records and file through MTD-compatible software. If you’re still using spreadsheets linked to bridging software, consider moving to a fully integrated system. MTD for Income Tax Self Assessment begins in April 2026 for those with qualifying income over £50,000.
Companies House deadlines
These are separate from HMRC and have their own penalty regimes.
| Filing | Deadline | Penalty |
|---|---|---|
| Annual accounts (private company) | 9 months after financial year-end | £150 to £1,500 (escalating) |
| Annual accounts (public company) | 6 months after financial year-end | £750 to £7,500 (escalating) |
| Confirmation statement | Within 14 days of the review period anniversary | £5,000 fine and potential strike-off |
| Notification of changes (directors, address, shares) | Within 14 days of the change | Compliance risk |
Companies House has been increasingly proactive about striking off companies that fail to file. Don’t let your confirmation statement lapse.
The Northern Ireland angle
Tax deadlines are set at the UK level, so NI businesses face exactly the same dates as those in England, Scotland, and Wales. However, there are a few NI-specific considerations.
Invest NI grant reporting. If your company has received Invest NI funding, you may have additional reporting obligations. These don’t follow the standard tax calendar and vary by programme. Check your letter of offer for the specific dates and requirements. Missing a grant reporting deadline can trigger clawback provisions.
Rates bills (business rates). While not a tax in the HMRC sense, business rates in Northern Ireland are administered by Land and Property Services (LPS), not local councils as in England. Rate bills typically arrive in April, with payment options including monthly direct debit (April to January, ten instalments). The system is different enough from England and Wales that businesses expanding from GB sometimes get caught out.
Regional differences in HMRC offices. HMRC’s main NI office is in Belfast. While most interactions are now digital, if you need to deal with HMRC in person or by post, the Belfast office handles NI-specific queries. For complex issues, particularly around cross-border trade with the Republic of Ireland, the Belfast office has dedicated staff.
Cross-border trade considerations. If your NI business trades with the Republic of Ireland, the Windsor Framework means you’re operating under a unique set of rules. VAT on goods moving between NI and the EU follows different procedures from the rest of the UK. This doesn’t change your filing deadlines, but it does add complexity to your VAT returns. Make sure your software and processes are set up correctly.
Tips for staying on top of deadlines
1. Use a shared calendar. Put every deadline into a shared calendar that your finance team (even if that’s just you) can access. Set reminders for two weeks before and one week before each deadline.
2. File early, pay on time. There’s no benefit to filing at the last minute. Filing early gives you time to identify issues, correct errors, and plan for payments. You don’t have to pay early just because you file early.
3. Set up direct debits. HMRC allows direct debit payments for Self Assessment, VAT, and PAYE. This removes the risk of forgetting a payment date. For Self Assessment, you can set up a Budget Payment Plan to spread the cost across the year.
4. Keep your records current. The biggest reason businesses miss deadlines isn’t forgetfulness; it’s that their bookkeeping isn’t up to date when the deadline arrives. Monthly bookkeeping (even if it’s just an hour) makes year-end painless.
5. Know your penalty exposure. HMRC’s penalty regime is points-based for VAT (from 2023 onwards) and increasingly moving towards this model for other taxes. Each late submission earns a point. Reach the threshold and you get a £200 penalty, with further penalties for each subsequent late submission. The thresholds are:
| Filing frequency | Points threshold |
|---|---|
| Annual | 2 points |
| Quarterly | 4 points |
| Monthly | 5 points |
6. Work with your accountant proactively. Don’t wait until the deadline to send your records. The earlier your accountant has your information, the better the advice they can give you, and the less you’ll pay in rush fees.
How Arro Group can help
We manage the full compliance calendar for our clients, from Self Assessment to corporation tax to VAT, with built-in reminders and regular check-ins so nothing slips through the cracks. If you’d like to stop worrying about deadlines and start focusing on running your business, we’d be happy to take that off your plate.