Quick answer
Filing yourself works if your tax affairs are simple and you are comfortable with HMRC’s online system. An accountant is usually worth it with several income sources, rental profits, dividends, capital gains or when you are short on time.
Updated October 2026 · Figures based on 2025/26 rates
Filing your Self Assessment doesn’t have to be stressful. Let our qualified accountants handle everything — accurately and on time.
Reasons to do it yourself
One income source, clear records, no complicated reliefs, and time to learn the process. HMRC’s online service is free. If you can tick all four of those, DIY is a defensible choice — just start early and keep a copy of your filed return and the tax calculation.
Reasons to use an accountant
Complex income, fear of mistakes, tight deadlines, or wanting every allowance claimed. An accountant also handles HMRC letters. If any of these apply, get a fixed fee quote before the autumn rush so you can compare properly.
Want an accountant to handle this for you?
Fixed price from £199 + VAT. Done for you online by UK accountants.
The cost of errors
Mistakes can lead to penalties, interest and enquiries, and missed claims can cost more than a professional fee. The most expensive mistakes are usually the claims you never knew existed, not arithmetic slips.
A middle option
Some people use an accountant for a first return, then follow the same structure themselves in later years. This works best when your affairs stay similar year to year.
When doing it yourself works well
Filing your own Self Assessment return is perfectly possible, and for many people with simple affairs it is the sensible choice. If you are an employee with one small side income, a single rental property with straightforward costs, or a sole trader with clear records and no unusual transactions, the HMRC online service guides you through the questions. The main costs are your time and the risk of getting something wrong. You need to be comfortable finding your own records, understanding which expenses are allowable, and checking the final calculation. If you can do that and you start well before the deadline, DIY can be a reasonable route. Our guide for first-time filers is a useful starting point.
When an accountant earns their fee
An accountant becomes more valuable as the return becomes more complicated. Examples include company directors with dividends, landlords with mortgage interest and repairs to classify, people with capital gains, anyone with foreign income, those affected by the High Income Child Benefit Charge, and sole traders who are unsure about expenses or about when Making Tax Digital will apply to them. In those cases, a professional can spot reliefs you might miss, avoid errors that could lead to HMRC enquiries, and give you a clear view of what you will owe and when. An accountant is also useful if you simply want to hand the job over and know it has been done correctly. For an idea of what to expect, see our guide to how an accountant can save you tax.
Worked example: counting the real cost
This is an illustrative example for a sole trader in England with £35,000 profit. The figures show how to compare the two routes honestly, not a guarantee of what an accountant will find.
| Item | DIY | With an accountant |
|---|---|---|
| Fee | £0 | £199 + 20% VAT = £238.80 |
| Time spent, valued at £30 an hour | 8 hours = £240 | 1 hour = £30 |
| Expense claims found | £1,200 | £2,100 (home working £312, mileage £450 and training £138 extra) |
| Tax and NI saved on claims at 26% | £312 | £546 |
| Net position (saving less fee and time) | £312 – £240 = £72 | £546 – £238.80 – £30 = £277.20 |
The difference comes from the extra £900 of claims found, which at 26% (20% income tax plus 6% Class 4 NI) is worth £234. Your situation will differ, and some people will find the DIY route cheaper, especially if their records are already tidy. The point of the exercise is to include your own time and the risk of missing claims, not just the headline fee. For more on pricing, see how much a Self Assessment accountant costs and fixed fee versus hourly accountants.
Common mistakes
- Choosing on price alone without checking what is included, such as whether the fee covers filing, advice and a tax bill estimate.
- Starting a DIY return in the last week of January and running into login problems.
- Assuming an accountant will chase you for records. You still need to supply them.
- Not asking about qualifications. It pays to check who will actually prepare your return. Use our questions to ask before hiring an accountant.
- Not keeping a copy of the filed return and calculation.
- Treating the accountant as responsible for deadlines you have not given them the information for.
Practical checklist for deciding
- List your income sources and decide whether any are unusual or high-value.
- Estimate how many hours you would spend, and what your time is worth.
- Check whether you are confident about expenses and allowances.
- Ask for a fixed fee quote that spells out exactly what is included.
- Decide early. Both routes work better if you start before the autumn.
How SATR can help
SATR offers a fixed fee from £199 + VAT, qualified UK accountants and online filing, so you know the cost up front. You can order online in minutes, or read about our service for sole traders.
This is general information, not personal tax advice.
Thinking about the longer term
The choice does not have to be permanent. Some people file their first return themselves, discover how much time it takes, and then hand it over the following year. Others use an accountant while their affairs are complicated, for example in the first year of trading or after buying a property, and go back to DIY once things settle down. With Making Tax Digital for Income Tax starting from 6 April 2026 for qualifying income over £50,000, and widening to £30,000 from April 2027 and £20,000 from April 2028, the quarterly reporting requirements may also change what is practical for you, so it is worth checking current HMRC guidance on when you will be affected. Whichever route you choose, keep tidy records throughout the year, because that makes every option cheaper and less stressful.
Frequently asked questions
Is it cheaper to file myself?
The direct cost is lower — filing through HMRC is free — but your time and the risk of missing reliefs can outweigh the saving. Work out your hours at a realistic hourly rate before deciding.
Can an accountant fix mistakes from past years?
Yes. They can review earlier returns and amend them, normally within 12 months of the statutory filing deadline. Older years can sometimes be corrected through overpayment relief, but the conditions are strict, so ask promptly.
Can I switch from DIY to an accountant part way through?
Yes. You can hand your information to an accountant at any point before the deadline, but the later you leave it the less time there is to gather records and fix problems. If you are close to the deadline, warn them upfront.
Will an accountant guarantee I pay less tax?
No honest accountant can guarantee that. They can make sure you claim the reliefs and allowances you are entitled to and avoid mistakes, but the tax you owe depends on your actual income and costs.
Does using an accountant mean I am responsible for nothing?
You remain legally responsible for your return, so you must give complete and accurate information and review what is filed on your behalf.
Don’t leave your tax return to the last minute. Avoid penalties, save time, and let an expert take care of it for you.
The Bottom Line
DIY works when your affairs are simple and you start early; an accountant earns their fee when your income is complex, your time is scarce or you want the certainty of a professional review. Count the true cost — including your own time — before deciding.
If you would rather hand the whole job over, SATR prepares and files your Self Assessment for a fixed fee from £199 + VAT — done online by qualified UK accountants. Order online now or see our Self Assessment pricing.
