Reference · 2025/26 Tax Year

UK Tax Calendar

Every key tax date in one place. Bookmark this page — missing these deadlines costs money. The tax year runs from 6 April to 5 April the following year.

2025/26 tax year (6 April 2025 – 5 April 2026). Always verify key deadlines at gov.uk as dates can change.
5 AprISA allowance deadline — unused allowance is lost forever at midnight
6 AprNew tax year begins — new ISA allowance, new CGT exemption
31 JanOnline self-assessment deadline AND payment deadline — penalties from day 1 late
April 2025Start of 2025/26 tax year
5
ISA deadline — last day of 2024/25ISA
Final day to use your 2024/25 ISA allowance (£20,000 S&S ISA + £4,000 LISA). Unused allowance is permanently lost at midnight. JISA deadline also applies (£9,000 per child).
6
New 2025/26 tax year beginsTax Year
New ISA allowances open (£20,000 adult, £4,000 LISA, £9,000 JISA). New CGT annual exemption (£3,000). New dividend allowance (£500). New Personal Allowance applies.
6
P60 — employer deadline to issuePAYE
Your employer must issue your P60 (summary of pay and tax for the year ending 5 April) by 31 May. Check it carefully — employer errors on P60s are common.
May 2025
31
P60 must be issued by todayPAYE
Employers must provide P60s to all employees still in employment on 5 April by 31 May. Use this to check your tax code and total tax paid are correct.
July 2025
31
Second payment on accountSelf-Assessment
Second of two advance payments toward your 2025/26 tax bill, based on 50% of your 2024/25 bill. Only applies if you made payments on account last January. Late payment incurs interest immediately.
6
P11D deadline for employersBenefits in Kind
Employers must report benefits in kind (company cars, private medical insurance, expenses) on P11D forms by 6 July. You should receive a copy if benefits apply to you.
October 2025
5
Register for self-assessment — DEADLINESelf-Assessment
If 2024/25 was your first year needing self-assessment (self-employment income over £1,000, income over £100,000, untaxed income etc.) you must register with HMRC by 5 October 2025. Missing this deadline risks penalties.
31
Paper self-assessment deadlineSelf-Assessment
If filing a paper tax return for 2024/25, it must reach HMRC by 31 October. Most people file online (deadline 31 January) — strongly recommended for the later deadline and automatic tax calculation.
December 2025
30
PAYE coding notice deadline (online filing)PAYE
If you want HMRC to collect tax owed (under £3,000) via your PAYE tax code rather than a lump sum, file your online return by 30 December. Useful if you'd prefer the tax collected in monthly instalments through your salary.
January 2026Most important month of the year
31
Online self-assessment FILING deadlineSelf-Assessment
The most critical tax date of the year. File your 2024/25 online return by midnight on 31 January 2026. Miss it and you face an immediate £100 penalty — then £10/day after 3 months, then further penalties at 6 and 12 months. No excuse removes the penalty.
31
Tax PAYMENT deadline for 2024/25Self-Assessment
Any tax owed for 2024/25 must be paid by 31 January 2026. This includes the balancing payment plus the first payment on account for 2025/26. Unpaid tax attracts interest immediately, plus 5% surcharge penalties at 30 days and 6 months late.
31
First payment on account for 2025/26Self-Assessment
If your previous year's tax bill exceeded £1,000 and less than 80% was deducted at source, you must make advance payments on account. The first (50% of last year's bill) is due 31 January alongside the balancing payment.
April 2026End of 2025/26 tax year
5
2025/26 ISA deadline — last chanceISA
Final day to use your 2025/26 ISA allowances. Midnight 5 April — any unused allowance is lost permanently. If you have spare cash available and haven't used your full £20,000, this is your last opportunity.
5
Pension carry forward — last chance for 2022/23Pension
You can carry forward unused annual pension allowances for up to three years. After 5 April 2026, you can no longer use any remaining 2022/23 allowance. If you have a large pension contribution to make, act before this date.
6
2026/27 tax year beginsTax Year
New ISA allowances, CGT exemption, and dividend allowances open. New P60 cycle begins.

Dates that don't move — remember these always

DateWhat happensMiss it and...
5 AprilISA allowance expires (£20,000 adult, £9,000 JISA, £4,000 LISA)Allowance lost permanently — cannot be carried forward
6 AprilNew tax year begins — new allowances, new thresholdsN/A — automatic
5 OctoberSelf-assessment registration deadline (first-time filers)£100 minimum penalty — and you still have to file
31 OctoberPaper self-assessment deadlineAutomatic penalty — file online instead (31 January deadline)
31 JanuaryOnline self-assessment filing AND payment deadlineImmediate £100 penalty; interest on unpaid tax from midnight
31 JulySecond payment on accountInterest charged from 1 August
Official References
gov.uk — Self Assessment deadlines and penalties gov.uk — ISA allowance rules gov.uk — How to pay your self-assessment tax bill gov.uk — Pension annual allowance carry forward