8 ways to make filing your tax return easier

Filing a self-assessment tax return can be stressful. Our survey found that more than four in 10 Which? members who do it themselves feel that way.

In a separate question, three in 10 members who file their own self-assessment said they find the process difficult. Among this group, confusing terminology and rules were the most common issue, followed by keeping track of paperwork and using HMRC’s online system. 

The findings are based on responses from 293 Which? members who said they complete their own self-assessment tax return, drawn from a wider survey of 1,240 members carried out in January 2026.

Here, Which? shares eight practical ways to make the self-assessment deadline a little less taxing, along with what to do now if you think you might miss the 31 January deadline.

1. Consider whether you need to do it yourself

You don’t have to complete your self-assessment tax return on your own.

Many people presume that accountants are only for big businesses or very high earners, but they can also help individuals with personal tax returns. As well as completing forms and guiding you through payment, an accountant can help check you’re not overpaying tax and that you’re claiming the right reliefs and allowable expenses.

That said, it is a paid service. Although fees can sometimes be claimed as a business expense, if your tax affairs are fairly straightforward, completing the return yourself may be perfectly manageable.

There are also several online calculators and tools available to help you work out your self-assessment tax liability for a small fee. For example, Which? members can use Go Simple Tax's tool for £34.99.  

• Find out more: How to fill in a self-assessment tax return

2. Know the deadlines

Understanding the key deadlines helps you plan ahead and avoid penalties. Although most of them have now passed, and just the deadline for online remains, for the 2024-25 tax year, the main dates are:

• 31 July 2025 - deadline for 'payments on account' for 2024-25 tax year
• 5 October 2025 - deadline to register for self-assessment for the 2024-25 tax year
• 31 October 2025 - deadline for paper tax return for 2024-25 tax year
• 31 January 2026 - deadline for online self-assessment tax return for 2024-25.

If you miss the payment deadline, you may have to pay a £100 late-filing penalty – even if you have no tax to pay or the tax has already been paid.  

For the 2025-26 tax year, the key dates are 31 July, 5 October and 31 October 2026, with the online self-assessment tax return deadline being 31 January 2027. 

• Find out more: UK income tax rates 2025-26 and 2024-25

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3. Make sure you have everything you need

Self-assessment requires pulling together a lot of information, so it’s worth checking what you’ll need before you start.

Information you’ll need to submit includes things such as: 

• Your income for the tax year (6 April 2024 - 5 April 2025)
• Unique Taxpayer Reference (UTR)
• National Insurance number  
• Benefits from your employer
• Dividends
• Interest on savings
• Income from rental properties
• Expenses
• Income from trusts
• Income from pensions
• Student loan plan and any repayments 
• Gift Aid donations.

Find out more: Tax reliefs – how to reduce your tax bill

4. Keep receipts safe and organised 

If you’re self-employed, receipts for business expenses such as travel, uniforms or equipment are essential, as they can reduce your tax bill. However, not all costs count. HMRC guidance makes clear that entertaining clients, suppliers or customers, including buying food or drinks for meetings, can’t be claimed.

Whether you use an accountant or file yourself, you should keep clear records as evidence for HMRC. 

Scanning paper receipts and storing them digitally in labelled folders can help, particularly if your turnover exceeds £85,000 and you’re required to categorise costs.

• Find out more: How to calculate your tax bill

5. Be clear which sections apply to you

You don’t need to complete every section of a tax return. Knowing which parts apply to your circumstances can make the process feel more manageable. 

Everyone completes the main SA100 form, but you may also need additional sections covering employment, self-employment, property income, partnerships, foreign income, capital gains or trusts. HMRC guidance explains which supplementary pages apply in each case.  

• SA102: Employment (Employee or Company Director)
• SA102M: Ministers of religion
• SA102MP: Parliament (MP or Minister)
• SA102MS: The Senedd Cymru (Welsh Parliament)
• SA102MLA: Northern Ireland Legislative Assembly
• SA102MSP: Scottish Parliament
• SA103L: Lloyd’s underwriters
• SA109: Residence, remittance basis etc (Non-UK or dual resident)
• SA101: Additional information (less common income, deductions, and reliefs)
• SA103S / SA103F: Self-employment (short or full)
• SA104S / SA104F: Partnership (short or full)
• SA105: UK property income
• SA106: Foreign income or gains
• SA107: Trusts etc. (income from a trust, settlement, or estate)
• SA108: Capital Gains summary
• SA110: Tax calculation summary

Find out more: Online tax returns explained

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6. Choose the right payment method 

If you owe tax, how you pay matters – especially close to the deadline. Some payment methods take longer to process than others.

The fastest methods will get the money over to HMRC the same or next day. These are: 

• Online or mobile banking (Faster Payments)
• Chaps
• Debit card or corporate credit card (online)
• In-person at your bank (requires an HMRC paying-in slip)

Within 3 working days:

• Bacs
• Existing direct debit (already authorised)
• Cheque (allow extra time for postal delays)

Within 5 working days:

• New direct debit (first-time setup)

As 31 January 2026 falls on a Saturday, payments usually need to reach HMRC by Friday 30 January. Faster Payments and card payments are the main exceptions, as they can be processed over weekends.

• Find out more: Tax codes and what they mean

7. Save your progress and come back to it

Self-assessment can be time-consuming. In our survey of members who complete their own self-assessment tax return, 33% said they spend one to three hours a year working on it, 27% said it takes four to six hours, and 31% said they spend seven hours or more.

Starting early gives you time to save your progress, step away and double-check figures before submitting. This can help minimise mistakes.

If you spot an error after filing, you can amend your return for up to 12 months after the original deadline. For the 2024-25 tax year, amendments can be made until 31 January 2027. Any underpayment will need to be settled, while overpayments are refunded.

• Find out more: Pension tax calculator

8. Seek out free help

Although more than a third of members in our survey said they felt well supported by official guides and resources, nearly 32% said they still struggle and feel they have to navigate the self-assessment process on their own. If that sounds familiar, there is free help available.

Which? tax guides explain what you need to know when completing a self-assessment tax return, including how to claim allowable expenses, report different types of income and avoid common mistakes. Which? Money members can also contact our Money Helpline for personalised guidance from trained advisers. 

HMRC provides free webinars, videos and digital assistants to help taxpayers through the process. 

You can also use MoneyHelper, a free and impartial service backed by the government and provided by the Money and Pensions Service.

 The charity TaxAid (formerly Tax Help for Older People) runs a dedicated helpline for people who need extra support with their tax affairs.

Expert view

Tell HMRC if you are going to miss the deadline

Ruby Flanagan, Which? tax writer, says: 'If you fail to submit, you face an automatic penalty. However, you may be able to evade a fine if you tell HMRC ahead of 31 January. 

'You’ll need to explain your situation and why you're unable to make the deadline. Under self-assessment rules, if you have a ‘reasonable excuse’ such as a serious illness, bereavement, major IT failure, or problems with HMRC's services, the tax office may waive or suspend the penalty. 

'However, you can’t blame your accountant, as HMRC holds you wholly responsible. If you can’t cover the bill, you can set up a time-to-pay arrangement with HMRC, which will spread the costs over the coming tax year. 

‘You should try to pay any penalties and tax owed as soon as possible, to avoid further interest and escalating charges. If you believe a penalty is unfair, you can appeal online or by using form SA370, but have the penalty amount ready to pay while you're in the process of appealing.'