Self Assessment for the 2024/25 tax year comes with a firm deadline of 31 January 2026, the date HMRC requires both your online filing and any tax owed to be paid. Missing it leads to automatic penalties, even if you owe nothing, which is why preparing early protects you from avoidable fines and last-minute stress.
This guide is written for sole traders, landlords, company directors, contractors, and anyone earning untaxed income from side hustles, digital work, crypto trading, or self-employment. Whether you’re new to the process or want a smoother experience this year, you’ll find clear steps, practical tips, and UK-specific guidance to help you stay compliant.
With the key deadline set and the filing window open from April 2025, now is the ideal time to get organised. Let’s start with the dates you need to mark on your calendar.
Key Deadlines You Must Know for the 2026 Self Assessment
The 2024 to 2025 tax year covers income earned between 6 April 2024 and 5 April 2025. HMRC allows you to submit your return as soon as the tax year ends, but the deadlines are fixed and must be followed.
- 31 October 2025: This is the final date HMRC accepts paper tax returns for the 2024 to 2025 tax year.
- 31 January 2026: This is the final date to submit your online Self Assessment tax return. This is also the final date to pay any tax you owe for 2024 to 2025, including your balancing payment and your first payment on account for 2025 to 2026 if HMRC requires it.
Now that the key timings are clear, the next section explains who must file a return for the 2024 to 2025 tax year.
Who Needs to File a 2024 to 2025 Self Assessment
HMRC requires a Self Assessment tax return when you receive income that has not already been taxed or when your circumstances fall within specific criteria. For the 2024 to 2025 tax year, you must file if any of the following apply.
- You are a sole trader and earned more than £1,000 in self-employed income during the tax year. This threshold relates to HMRC’s Trading Allowance and applies even if your business is very small.
- You work as a partner in a business partnership.
- You are a landlord earning rental income from UK or overseas property. This includes traditional rentals, holiday lets, Airbnb income, rooms rented in your home, and any shared accommodation income above the Rent a Room threshold.
- You are a company director, unless you are a director of a non-profit organisation and receive no pay or benefits.
- You receive side income that has not been taxed. This includes freelance work, digital services, content creation, tutoring, online selling, affiliate payments, tips, commission, gig work and similar activities.
- You have savings interest, dividends, or investment income that exceeds HMRC’s tax-free allowances.
- You receive foreign income, even if it is small, and even if tax has already been paid overseas.
- You made capital gains from selling shares, property, cryptoassets or other investments above HMRC reporting thresholds.
- You claim the High Income Child Benefit Charge, which applies when your income is above HMRC’s specified limit.
- You receive a notice to file from HMRC. When HMRC issues this notice, you must submit a return even if your income is below the usual thresholds.
Understanding whether you must file is the first step. If any of these apply to you, the next section explains the documents and records you need before completing your Self Assessment.
Wondering how VAT works for small businesses? You can learn the difference between the VAT Flat Rate Scheme and Standard VAT in our detailed guide.
Documents and Records You Need Before Filing
Before you start your 2024 to 2025 Self Assessment, HMRC expects you to have clear records of your income and any allowable costs. Having everything ready ensures your return is accurate and reduces the chance of penalties or HMRC enquiries.
- Your Unique Taxpayer Reference and Government Gateway login: You need your UTR to file a return and your Government Gateway account to access HMRC’s online service. Without these, you cannot submit your Self Assessment.
- Income records from employment or self-employment: This includes P60 or P45 forms from employers and full records of invoices, sales, bank statements and expenses if you are self-employed.
- Rental income and property expense records: Tenancy agreements, rental statements, repair costs, letting agent fees and mortgage interest are all important for accurate reporting.
- Savings, dividends and other investment income: Banks and investment platforms provide annual summaries that show interest and dividends received. Include these if they exceed HMRC allowances.
- Trading, crypto or side-income activity: If you earn through freelancing, online platforms, trading or cryptoassets, keep transaction logs, receipts and platform summaries to ensure your figures are correct.
Collecting these documents early makes the filing process smoother and helps prevent mistakes that can lead to penalties.
If you need help reviewing or organising your records, you can speak with a personal tax specialist at eAccounts UK for support.
How to File Your Self Assessment Online Step by Step
HMRC allows you to file your Self Assessment online through your Government Gateway account. Following a clear process helps reduce errors and ensures your return is accepted the first time.
1. Register for Self Assessment if you have not filed before
If you are new to Self Assessment, you must register with HMRC to receive your Unique Taxpayer Reference. Registration deadlines apply, so do this early to avoid delays.
2. Enter all sources of income for the 2024 to 2025 tax year
This includes employment income, self-employment profits, rental income, savings interest, dividends, foreign income and any side earnings. HMRC requires full and accurate reporting of all untaxed income.
3. Enter your allowable expenses
If you are self-employed or a landlord, enter the expenses you can claim. This may include tools and equipment, mileage, office costs, repairs, insurance and agent fees. Correctly entering expenses reduces your taxable profit.
4. Claim any tax reliefs you are entitled to
This may include pension contributions, charitable donations through Gift Aid or specific reliefs such as Married Couple’s Allowance where eligible. These reliefs can reduce your overall tax bill.
5. Review your return carefully and submit it to HMRC
Check all figures, income sources and expenses before submitting. Once you are satisfied, submit your return through your online HMRC account. HMRC will confirm receipt immediately.
6. Pay any tax due by 31 January 2026
This payment includes your balancing payment for 2024 to 2025 and your first payment on account for 2025 to 2026, if applicable. Paying on time avoids late payment interest and penalties.
The next section explains the allowable expenses you can claim to help reduce your tax bill.
Allowable Expenses You Can Claim as a Sole Trader or Landlord
Claiming the correct expenses reduces your taxable profit and helps ensure you only pay the tax you owe. HMRC allows a wide range of everyday business costs for both sole traders and landlords, provided the expenses are wholly and exclusively for business use.
The table below shows some of the most common allowable expenses for self-employed individuals and property owners.
| Expense Type | Sole Traders | Landlords |
| Office and home-working costs | Heating, electricity, internet, stationery and office equipment | Not normally allowed unless you run a registered office from the property |
| Travel costs | Mileage, fuel, parking, public transport for business journeys | Mileage for property visits, travel to manage repairs or inspections |
| Professional services | Accounting fees, legal fees for business matters, software subscriptions | Letting agent fees, accounting fees, legal costs for tenancy agreements |
| Repairs and maintenance | Repairs to equipment and tools, replacement of small items | Repairs to the property, maintenance, service charges, safety certificates |
| Insurance | Public liability insurance, business insurance | Landlord insurance, building insurance if you are responsible |
| Marketing and advertising | Website costs, online ads, printed materials | Advertising for tenants or listing fees |
| Phone and communication | Mobile and broadband used for business | Mobile and broadband used to manage the property |
| Mortgage interest | Not applicable | A portion of mortgage interest can be claimed through finance cost relief |
Correctly claiming expenses helps reduce your tax bill, but many people miss items they are entitled to. If you want to maximise your legal deductions and stay compliant with HMRC rules, the team at eAccounts UK can support you throughout the process.
Common Mistakes That Lead to HMRC Penalties
Even small errors in a Self Assessment submission can trigger HMRC penalties, late fees or compliance checks. Understanding the most frequent mistakes helps you avoid issues and keep your tax record clean.
Missing income
HMRC cross-checks your tax return against information from employers, banks, investment platforms and other third parties. If you forget to include employment income, rental income, dividends, savings interest or untaxed side earnings, HMRC will detect the gap. Missing income can lead to underpaid tax, interest charges and penalties for inaccurate reporting.
Incorrect expense claims
Expenses must be wholly and exclusively for business use. Claiming personal costs, estimating figures without receipts or including capital improvements as repairs can result in HMRC disallowing the claim.
If the error appears careless or deliberate, penalties may follow. Landlords often make mistakes by claiming full mortgage payments instead of claiming only the allowable finance cost relief.
Forgetting student loan information
If you have an outstanding student loan and your income is above the repayment threshold, HMRC requires you to include this on your Self Assessment. Forgetting to do so means your loan repayments will be incorrect, and HMRC may issue a recalculation or charge late repayment interest. This is a common oversight for freelancers and people earning mixed income.
Underestimating payments on account
Payments on account apply when you owe more than one thousand pounds in tax for the previous year. If you do not calculate these correctly, you may pay too little and face interest on the unpaid amount. Many taxpayers forget that payments on account are based on the current year’s liability, not their estimates for the next year, which leads to unexpected bills.
Not checking your National Insurance contributions
Self-employed taxpayers pay Class 2 and Class 4 National Insurance through their Self Assessment. If you forget to review your NI position, you may underpay and face additional charges. Incorrect NI reporting can also affect your future entitlement to the State Pension and other benefits.
These mistakes are avoidable with careful preparation and a clear understanding of HMRC rules. The next section covers the penalties HMRC applies when returns or payments are late.
Penalties for Late Filing or Late Payment
HMRC charges several types of penalties when a Self Assessment tax return or tax payment is late. These apply even if the amount of tax owed is small.
- One hundred pound initial fine: This is charged immediately if your online return is not submitted by 31 January 2026, even when no tax is due.
- Daily penalties after three months: If the return is still missing three months after the deadline, HMRC can apply daily charges for up to ninety days.
- Percentage penalties for long delays
Additional penalties apply when the return reaches six months and twelve months late. These are calculated as a percentage of the unpaid tax. - Interest on unpaid tax: Interest begins on any outstanding tax from 1 February 2026 and continues until the full amount is paid. HMRC updates the interest rate regularly.
These penalties increase quickly, so filing and paying on time is the best way to avoid unnecessary costs.
What To Do If You Can’t File or Pay by 31 January 2026
If you cannot meet the Self Assessment deadline, taking quick action helps reduce penalties and interest.
- File your tax return as soon as possible: Submitting the return immediately stops additional late filing penalties. You can file even if you cannot pay the tax yet.
- Make a part payment if you can: Paying even a portion of the bill reduces the interest that will build on the remaining balance.
- Set up a Time to Pay arrangement: HMRC allows most taxpayers to spread their tax bill across monthly instalments. This can usually be arranged online if your bill is within HMRC’s limits.
- Contact HMRC early for assistance: If you know you will miss the deadline, speak to HMRC before penalties increase. HMRC may consider reducing penalties if you have a reasonable excuse.
- Ask an accountant to review any penalties issued: An accountant can check whether the penalty is correct and, if suitable, help you request a reduction or cancellation.
If you want help managing late filing issues or dealing with HMRC, the team at eAccounts UK can guide you through the next steps and provide expert support.
Why Many Britons Hire an Accountant for Self Assessment
Many people choose to work with an accountant because it removes the uncertainty that often comes with Self Assessment. An experienced accountant ensures your return is accurate, checks that all income has been recorded correctly and confirms that you are claiming every relief you are entitled to. This reduces the risk of HMRC penalties and helps you avoid mistakes that are easy to overlook when managing your own finances.
Hiring an accountant also saves time, especially if you have multiple income sources, rental properties, side earnings or more complex tax situations. Accountants can communicate with HMRC on your behalf, handle queries, and guide you through any issues that arise.
If you want a stress-free way to submit your return, you can file your Self Assessment with eAccounts UK by contacting our team.
Wrapping up
Filing your Self Assessment early is one of the most effective ways to avoid unnecessary pressure and ensure everything is completed correctly. Gathering your records ahead of time gives you space to check figures properly, claim the right expenses and avoid the penalties that can build when deadlines are missed. With the 2024 to 2025 tax return due on 31 January 2026, planning now means you can approach tax season with confidence instead of last-minute worry.
The Self Assessment process can be straightforward when you understand what HMRC requires, but it becomes much easier when you have expert support behind you.
If you want a smooth and stress-free filing experience, the team at eAccounts UK can help you prepare your documents, complete your return and manage any communication with HMRC.
FAQs
When is the deadline for filing the 2024 to 2025 Self Assessment?
The deadline for submitting your online return and paying any tax due is 31 January 2026, which HMRC treats as the final cut-off for all digital Self Assessment submissions.
Who must complete a Self Assessment tax return?
nyone who earns untaxed income such as sole traders, landlords, company directors or individuals with side earnings must file a return for the 2024 to 2025 tax year.
What happens if I miss the 31 January deadline?
If you miss the deadline, HMRC issues an automatic one hundred pound fine and additional penalties and interest begin to accumulate until your return and payment are completed.
Can I reduce my tax bill?
You can legally reduce your bill by claiming all allowable expenses, applying tax reliefs you qualify for and including pension contributions that attract extra tax benefits.
Can an accountant file it for me?
Yes, an accountant such as eAccounts UK can manage every step of the process for you, from preparing your records to submitting the return and handling HMRC queries.
