To file your 2024/25 Self Assessment tax return, submit it online through HMRC by 31 January 2026 and pay any tax you owe by the same date.1GOV.UK. Self Assessment Tax Returns: Deadlines The 2024/25 tax year covers income received between 6 April 2024 and 5 April 2025. That single January date matters more than any other because it governs both filing and payment, and missing it triggers a £100 penalty straight away, even if you owe no tax.2GOV.UK. Self Assessment Tax Returns: Penalties
Check Whether You Need to File
Not everyone does. If all your income is handled by an employer through PAYE, you probably do not need a return. You do need to file if any of these applied to you during 2024/25:
- You worked as a sole trader and earned more than £1,000 in gross income before expenses.3GOV.UK. Tax-Free Allowances on Property and Trading Income
- You were a partner in a business partnership.
- You sold an asset at a profit and owe Capital Gains Tax.
- You or your partner received Child Benefit and the higher earner had adjusted net income above £60,000.4GOV.UK. High Income Child Benefit Charge
- You had untaxed income from renting property, tips, foreign sources, or savings and investments.
Dividend and savings income sit slightly apart. You have a £500 dividend allowance for 2024/25, and dividends only need reporting if they exceed both that allowance and any remaining Personal Allowance.7GOV.UK. Tax on Dividends Savings interest has its own Personal Savings Allowance — £1,000 for basic-rate taxpayers, £500 for higher-rate. Interest inside that allowance is tax-free. Above it, HMRC can sometimes collect the tax by adjusting your PAYE code rather than making you file.8GOV.UK. Tax on Savings Interest
Register First If You Have Never Filed
If this is your first Self Assessment return, or you did not need to file for 2023/24, you must register with HMRC by 5 October 2025.9GOV.UK. Check How to Register for Self Assessment Registration produces your ten-digit Unique Taxpayer Reference (UTR), which you will need to log in and file. Leaving this to the last minute is risky because the UTR arrives by post and can take a couple of weeks.
Gather Your Documents Before You Start
Filing is much smoother if you have everything to hand. Log in requires your UTR and your National Insurance number.10GOV.UK. Find Your UTR Number
For employment income, your P60 shows total pay and tax deducted over the year. Left a job during 2024/25? Your P45 from that employer covers earnings up to your leaving date. Benefits in kind — a company car, private medical cover, and similar — appear on your P11D.11GOV.UK. Your P45, P60 and P11D Form
If you are self-employed, pull together your sales invoices, receipts for allowable expenses like travel and equipment, and bank statements covering the business. The more organised your records were through the year, the shorter this task will be.
Other paperwork worth collecting: bank and building society interest certificates, dividend vouchers, rental income and expense records, pension contribution statements, and Gift Aid receipts. Gift Aid donations extend your basic-rate band, so higher-rate taxpayers can pick up extra relief through the return.
Pension Contributions Are Worth Checking
You can contribute up to £60,000 to pensions in 2024/25 with tax relief, capped at 100% of your UK taxable earnings.12GOV.UK. Pension Schemes Rates Your pension provider only reclaims basic-rate relief at source, so higher-rate and additional-rate taxpayers must claim the extra relief through Self Assessment. Skipping this step leaves money with HMRC that could be yours. If you flexibly accessed pension benefits during the year, the money purchase annual allowance restricts you to £10,000.
How to File Online
Most people file through HMRC’s online Self Assessment service. Sign in with your Government Gateway credentials, work through the sections that apply to you, and the system calculates what you owe as you go. You can save and come back later, which helps if you are still waiting on a dividend voucher or an interest certificate.13GOV.UK. File Your Self Assessment Tax Return Online
The main form is the SA100, with supplementary pages for specific income types such as self-employment, property, or foreign income.14GOV.UK. Self Assessment Tax Return Forms The online service works out which supplementary pages apply based on your answers, so you do not need to identify them in advance.
Foreign income belongs on the return if you are a UK resident with overseas earnings or gains. Any foreign tax already paid can be reclaimed through Foreign Tax Credit Relief, but only if you report the income.15GOV.UK. Tax on Foreign Income
Paper Filing Has an Earlier Deadline
You can still file on paper, but the deadline is 31 October 2025 rather than 31 January 2026.1GOV.UK. Self Assessment Tax Returns: Deadlines Print and complete the SA100, sign it, and send it to HMRC by tracked post. HMRC will process it and send you a calculation showing what you owe.
What the Return Will Calculate
Your Personal Allowance for 2024/25 is £12,570. For England, Wales, and Northern Ireland, income tax then runs at 20% on income between £12,571 and £50,270, 40% between £50,271 and £125,140, and 45% above £125,140.16GOV.UK. Income Tax Rates and Allowances for Current and Previous Tax Years Scotland sets its own rates and bands, ranging from a 19% starter rate to a 48% top rate, and Scottish taxpayers should check those separately.
One trap catches many higher earners. Adjusted net income above £100,000 reduces your Personal Allowance by £1 for every £2 over the threshold, wiping it out entirely at £125,140. The effective marginal rate on income between £100,000 and £125,140 works out at 60%.17GOV.UK. Income Tax Rates and Personal Allowances Pension contributions cut your adjusted net income and can restore the allowance, so if you are close to that range it is worth doing the maths before you file.
Self-employed filers also calculate Class 4 National Insurance on the return: 6% on profits between £12,570 and £50,270, and 2% on profits above £50,270.18GOV.UK. Rates and Allowances: National Insurance Contributions Class 2 contributions are now treated as paid automatically for most self-employed people, so your State Pension record is credited without a separate payment. If your profits are below £6,725, you can pay voluntary Class 2 to protect your record.19GOV.UK. Self-Employed National Insurance Rates
If you have a student loan, the return calculates repayments too, at 9% of income above the plan’s threshold (£26,900 for Plan 1, £29,385 for Plan 2, £33,795 for Plan 4, £25,000 for Plan 5) and 6% above £21,000 for a Postgraduate Loan.20GOV.UK. Repaying Your Student Loan: How Much You Repay
Paying What You Owe
Your balance for 2024/25 is due by 31 January 2026. HMRC accepts Direct Debit, online banking, and bank transfers using your UTR as the payment reference, along with debit card payments through the online service. Payment date is when the money clears with HMRC, not when you send it, so allow up to two working days for bank transfers.
Payments on Account
If your Self Assessment liability for 2024/25 exceeds £1,000 after any PAYE tax, you will also make payments on account toward the following year. Each one is 50% of your previous year’s Self Assessment tax and Class 4 NIC combined. The first is due on 31 January 2026 (alongside your 2024/25 bill) and the second on 31 July 2026.
First-time filers often find this January payment jarring: it is the full 2024/25 bill plus half again as an advance for 2025/26, which comes to 150% of a year’s tax in one go. You are exempt from payments on account if at least 80% of your income tax and Class 4 NIC was already collected at source. You can also apply to reduce them if you expect a lower bill next year, but reducing too far means HMRC charges interest on the shortfall.
Spreading or Delaying Payment
If you would rather pay in smaller chunks through the year, HMRC’s Budget Payment Plan lets you set up a weekly or monthly Direct Debit toward your next bill, with the option to pause for up to six months. You must be up to date on your current tax to use it.21GOV.UK. Pay Your Self Assessment Tax Bill
If you cannot pay the full amount by 31 January, a Time to Pay arrangement may help. For debts of £30,000 or less you can set one up online, provided your returns are up to date, you apply within 60 days of the deadline, and you agree to clear the balance within 12 months.22HM Revenue & Customs. HMRC Offers Time to Help Pay Your Tax Bill Larger debts or longer terms need a phone call. Interest still accrues, but the arrangement holds off enforcement.
Missing the Deadline
The £100 penalty applies immediately, even on a nil return. After that the charges stack:
- Up to three months late: the £100 stands.
- After three months: £10 per day, capped at £900.
- After six months: a further 5% of the tax due or £300, whichever is greater.
- After twelve months: another 5% of the tax due or £300, whichever is greater.
A return twelve months overdue can attract more than £1,600 in penalties before interest on unpaid tax is added.2GOV.UK. Self Assessment Tax Returns: Penalties
Late payment interest runs daily on any unpaid tax. From 6 April 2025, the rate is the Bank of England base rate plus 4%.23HM Revenue & Customs. HMRC Interest Rates for Late and Early Payments With the base rate at 3.75% in late 2025, that comes to 7.75%.24Bank of England. Bank Rate History and Data Older guidance may quote a lower figure because the rate before April 2025 was base plus 2.5%.
Fixing a Mistake After Filing
You have 12 months from the 31 January deadline to amend your return, whether you filed online or on paper.25GOV.UK. Self Assessment Tax Returns: If You Need to Change Your Return For 2024/25, that gives you until 31 January 2027. Beyond that, or for corrections to older years, you need to write to HMRC.
Keep Your Records
HMRC requires you to keep records for at least five years after the 31 January submission deadline for the relevant tax year.26GOV.UK. Business Records If You’re Self-Employed For the 2024/25 return, that means holding everything until at least 31 January 2031. If HMRC opens an enquiry, keep the records until it closes.
Making Tax Digital Is on the Horizon
Making Tax Digital for Income Tax does not affect the 2024/25 return you are filing now. From 6 April 2026, sole traders and landlords with combined self-employment and property income above £50,000 will need to keep digital records and file quarterly updates using compatible software.27GOV.UK. Sign Up for Making Tax Digital for Income Tax A second phase in April 2028 brings in those with income above £20,000.28GOV.UK. Find Out if and When You Need to Use Making Tax Digital for Income Tax If your income puts you above either threshold, choosing compatible bookkeeping software while you file this year’s return will make the transition easier.