TL;DR: The UK personal tax year ends on 5 April and the new tax year begins on 6 April. The date matters because most of the personal allowances, thresholds and contribution limits reset on that date. Anything not used by 5 April is generally lost. The main items to consider before the deadline are the ISA allowance (currently 20,000 pounds across all adult ISAs), the pension annual allowance (currently 60,000 pounds for most people, with carry-forward of unused allowance from up to three previous tax years), the capital gains tax annual exempt amount (currently 3,000 pounds), the dividend allowance (currently 500 pounds) and the Marriage Allowance election. Self assessment for the previous tax year follows on 31 January and 31 July.
Last reviewed May 2026
The UK personal tax year runs from 6 April to 5 April. The dates have a long historical origin (the change from the Julian to the Gregorian calendar in 1752 is the usually cited explanation) and they are unlikely to change. For most savers and taxpayers, the practical importance is that 5 April is a hard deadline for using a number of allowances that reset the following day.
Many of the things that need to be done before 5 April are simple but easy to miss because they happen at the busiest time of year. ISA contributions, pension contributions intended to use this year's allowance, capital gains realised in the year, charitable Gift Aid donations and Marriage Allowance elections are common examples. Missing the deadline does not affect the ability to plan in the new tax year; it just means this year's allowance is gone.
This guide sets out what 5 April actually means, the main items worth checking, the deadlines for the related self assessment process, and the things people often miss.
What the 6 April / 5 April dates actually mean
The personal tax year for income tax and capital gains tax starts on 6 April and ends on 5 April the following calendar year. The new tax year reset means the personal allowance, the personal savings allowance, the dividend allowance, the capital gains tax annual exempt amount, the ISA allowance and the pension annual allowance all start fresh.
For corporation tax the date is different: each company has its own accounting period, ending on whatever date its accounts run to. For VAT, the cycle depends on the registration. The 6 April / 5 April dates apply to personal taxation in the UK.
The State Pension and benefits also typically reset rates from early April, though usually on 6 April or the first Monday after, depending on the benefit. New tax codes and PAYE thresholds for the year start with effect from the first pay period beginning on or after 6 April.
ISA allowance: 20,000 pounds, use it or lose it
Each adult has an ISA allowance of 20,000 pounds for the tax year. This can be split between cash ISAs, stocks and shares ISAs, innovative finance ISAs and a Lifetime ISA (within the LISA's own 4,000 pound annual contribution cap). The 20,000 pound figure is the total contribution across all adult ISAs in the year.
The allowance does not roll forward. Whatever is unused on 5 April is gone. Investors who normally fund ISAs at the start of the new tax year (often the most efficient pattern, because it gives the longest period of tax-free growth) effectively still have the option of last-minute funding before 5 April for the previous year as well.
From the 2024 to 2025 tax year, savers can subscribe to multiple ISAs of the same type within the same tax year, subject to the overall 20,000 pound limit. Junior ISAs have their own separate annual allowance (currently 9,000 pounds) per child, also resetting at the start of each tax year.
Pension annual allowance and carry forward
The pension annual allowance is the cap on tax-relieved contributions to all of a person's registered pensions in a tax year. The standard annual allowance is currently 60,000 pounds. The annual allowance is tapered for high earners with adjusted income above 260,000 pounds, reducing by 1 pound for every 2 pounds of excess income, down to a minimum of 10,000 pounds.
Carry forward allows unused annual allowance from the previous three tax years to be added to the current year's allowance. To use carry forward, the saver must have been a member of a registered pension scheme in each of the relevant prior years and must have used up the current year's allowance first. Earnings in the current year still need to be sufficient to support tax relief on the contribution.
The money purchase annual allowance (MPAA) of 10,000 pounds applies once flexible income has been taken from a defined contribution pension. It restricts further DC contributions to 10,000 pounds a year and removes access to carry forward in respect of DC contributions. Anyone who has triggered the MPAA should plan accordingly.
Capital gains tax annual exempt amount and dividend allowance
The capital gains tax annual exempt amount allows individuals to realise gains up to a fixed threshold each year tax-free. The amount is currently 3,000 pounds, having been reduced from 6,000 pounds in the previous year. The exemption resets each tax year and unused amounts cannot be carried forward.
For investors with portfolios outside ISAs or pensions, the rule of thumb is to consider realising gains up to the annual exempt amount each year, particularly where the gains can be reinvested or used to fund ISA contributions. Spouses and civil partners can transfer assets between them without triggering CGT, allowing both annual exempt amounts to be used.
The dividend allowance is currently 500 pounds, having been progressively reduced in recent years. Above the allowance, dividends are taxed at the dividend rates (8.75 percent basic, 33.75 percent higher, 39.35 percent additional). The dividend allowance resets each tax year. As with savings interest, unused allowance does not carry forward.
Marriage Allowance and other elections
The Marriage Allowance lets a non-taxpayer spouse or civil partner transfer 10 percent of their personal allowance (currently 1,260 pounds) to their basic-rate-paying partner. The election can be backdated up to four tax years from the current year, so missed past years can be picked up at the same time. The application is made online through the GOV.UK personal tax account.
Other elections to consider before the year-end include Form 17 elections for jointly held property between spouses (where the actual beneficial ownership is not 50:50), Gift Aid carry-back claims (allowing a charitable donation in one tax year to be treated as paid in the previous tax year, useful if the donor was a higher-rate taxpayer in the earlier year), and certain trust elections.
The Gift Aid carry-back election in particular needs to be made by the time the donor's tax return for the previous year is submitted, so a donor who has already filed their return cannot make the election retrospectively. Anyone planning Gift Aid carry-back should make the election before submitting the return.
Self assessment deadlines that follow the year-end
The 5 April year-end is followed by a series of self assessment deadlines for the previous tax year. The first is the registration deadline of 5 October for anyone newly required to file a return. The paper return deadline is 31 October. The online return and payment deadline is 31 January.
For those with payments on account, the second payment on account is due on 31 July. Late payment attracts interest from the due date, and late filing attracts an automatic 100 pound penalty (and further penalties for prolonged delay).
For employers, the deadline for issuing P60s to employees who were on the payroll on 5 April is 31 May. P11Ds for taxable benefits in kind are due by 6 July, with the related Class 1A National Insurance payment due by 22 July (electronic) or 19 July (paper). Employers also need to update payroll systems for the new tax year codes.
Disclaimer: This article is general information about the UK tax year and the deadlines and allowances that fall around the 5 April year-end. It is not personal tax or financial advice. Allowances and thresholds change at fiscal events and the right action depends on individual circumstances. Anyone planning material year-end actions should check current HMRC guidance and consider professional advice.
Frequently asked questions
When does the UK tax year actually end?
The personal tax year ends on 5 April. The new tax year begins on 6 April. The dates apply to income tax, capital gains tax and most personal allowances. Corporation tax follows each company's accounting period, which is set separately.
Can I use last year's ISA allowance after 5 April?
No. The ISA allowance is annual and does not carry forward. Subscriptions made on 5 April count towards that year's allowance; subscriptions made on 6 April count towards the new year's allowance. Investors who want to use both years' allowances need to act before midnight on 5 April for the old year and on or after 6 April for the new year.
Can I carry forward an unused pension annual allowance?
Yes, in the case of the pension annual allowance. Unused annual allowance from up to three previous tax years can be carried forward to the current year, provided the saver was a member of a registered pension scheme in each of those years and provided the current year's allowance is used first. The money purchase annual allowance, where applicable, removes carry forward for further DC contributions.
Do I need to file my self assessment return immediately after 5 April?
The online filing and payment deadline is 31 January following the end of the tax year, which gives just under 10 months. The paper deadline is 31 October. Filing earlier is allowed and is often quicker because HMRC is less busy outside the January peak.
What happens if I miss the 5 April year-end?
Allowances that are use-it-or-lose-it (the ISA allowance, the dividend allowance, the CGT annual exempt amount, the personal savings allowance, the dividend allowance) cannot be reclaimed after 5 April. The pension annual allowance for the missed year can in some cases be used through carry forward in a future year, subject to the carry forward rules. Marriage Allowance for missed years can be backdated up to four tax years.
How we verified this
The 6 April to 5 April tax year dates and the structure of the personal tax allowances reflect the Income Tax Act 2007 and the Taxes Management Act 1970 as amended. ISA rules including the 20,000 pound annual subscription limit and the rules for multiple subscriptions to ISAs of the same type reflect the Individual Savings Account Regulations 1998 and HMRC's published ISA guidance. Pension annual allowance, carry forward and the money purchase annual allowance reflect Finance Act 2004 Schedule 36 and HMRC's Pensions Tax Manual. Capital gains tax and dividend allowance figures reflect current published rates. Self assessment deadlines reflect the Taxes Management Act 1970 and HMRC's published guidance. All figures should be reconfirmed on GOV.UK.
