Self Assessment Tax Returns
Last reviewed 17 July 2026
Compare self assessment accountants from £10/month — SA100 returns for sole traders, landlords and directors. Get matched before the January deadline.
Self Assessment is HMRC's system for reporting income not fully taxed at source. You may need a return if you have self-employment, rental, partnership or other untaxed income; being a company director alone does not make one compulsory. Online returns are generally due by 31 January after the tax year. Late filing can lead to a £100 initial penalty. An accountant can help check allowable expenses and payments on account.
What is Self Assessment, and who has to file?
Self Assessment is HMRC's process for reporting income that was not fully taxed at source. People with qualifying self-employment, rental, partnership or other untaxed income may need to file. Company directors do not have to file solely because they are directors; check your circumstances with HMRC.
Use HMRC's guidance to check whether you need to register. If you should have registered and missed the date, deal with it promptly. Supplementary pages may be needed for self-employment, property, capital gains or foreign income, and can affect an accountant's fee.
Do I need an accountant for Self Assessment?
You are not legally required to hire an accountant. You can file yourself if you understand the rules, have tidy records and can meet the deadline. Professional help may be useful for mixed income, rental property, company dividends or prior filing difficulties; compare the fee with the scope and complexity of your return.
The online deadline is 31 January following the tax year that ended on 5 April. Paper filing is earlier. Payments on account can surprise first-time filers. MTD for Income Tax from April 2026 adds quarterly digital updates for qualifying sole traders and landlords — a January-only relationship may not be enough once that starts.
How much does a self assessment accountant charge?
A standalone Self Assessment return typically costs £150–£350 per year. Bundled into a monthly sole-trader or director package it often looks like £10–£25 per month on our editorial benchmarks. Confirm whether the quote includes the SA100 only or also supplementary pages.
Landlords, capital gains and foreign income add pages and add fees. Do not compare a SA100-only quote with a full sole-trader package. Use the fee estimator, then three written quotes on the same scope.
When is the Self Assessment deadline?
For the 2025/26 tax year the online filing and payment deadline is 31 January 2027. Paper returns are due earlier. Late filing starts at a £100 penalty and can escalate if the return stays outstanding.
Payment and filing are the same date online for most people, but payments on account are a separate trap. If you cannot pay, still file — filing late and paying late are different penalties. Confirm current dates on GOV.UK; we last checked 17 July 2026.
What records do I need for a Self Assessment return?
Income, expenses with receipts, bank statements, dividend vouchers, and P60 or P45 if you also had employment. Digital records become mandatory under MTD for Income Tax if you are in a qualifying cohort. A shoebox in January is not a system.
Keep records for at least five years after the 31 January filing deadline. An accountant cannot invent missing invoices. The cheaper the quote, the more they will expect you to have already coded the year.
How does MTD change Self Assessment?
Qualifying sole traders and landlords must keep digital records and send quarterly updates from 6 April 2026 if income is over £50,000, with lower thresholds in 2027 and 2028. The year-end final declaration still exists. A once-a-year accountant may need to become a quarterly one.
MTD for VAT is already live if you are VAT-registered — that is a different regime. Limited companies do not file corporation tax through MTD. Confirm whether quarterly work is in your letter before April 2026.
How should I choose a Self Assessment accountant?
Pick a firm that files the pages you actually have — self-employment, property, or director dividends — and that will still be around in January. Check the professional-body register. Compare a one-off return quote with a monthly package if you also need books.
Rush fees near the deadline are normal. Switching in December is possible; it is not cheap. Authorise the accountant as your HMRC agent so they can see prior-year figures.
- List every income stream before you ask for a quote
- Compare a one-off SA100 with a monthly sole-trader package
- Confirm MTD quarterly work if you are in the 2026 cohort
- File early — do not wait for the last week of January
Typical cost
£10/mo – £25/mo
Rates checked 17 July 2026 · Benchmarks are editorial estimates — how we calculate them.
3031 firms offering self assessment
Register-listed firms that record this service. Verify credentials on the professional-body register before you engage.
Ratings and rankings are our editorial opinion, based on our publishedmethodology — they are not financial advice and firms cannot pay to change a score.Listings labelled Featured orReferral partner are paid placements; payment affects visibility only, never ratings or match results. We may receive a fee when you request quotes.Fees shown are indicative — always confirm directly with the firm.
1040 Tax Solutions Ltd
Tax consultants in Manchester · established 2017
121 Accounting Ltd
Accountants & auditors in London · established 2023
1226 Accounting Ltd
Accountants & auditors in Colchester · established 2021
123 Business Accounting Limited
Accountants & auditors in London · established 2018
1ST Accountants Ltd
Accountants & auditors in Morden, Greater London · established 2017
1ST Accounting Solutions Limited
Bookkeeping services in London · established 2010
1ST Stop Accountancy And Tax Services Bristol Limited
Accountants & auditors in London · established 2016
2021 Taxation Limited
Tax consultants in London · established 2021
24/7 Accountants Ltd
Accountants & auditors in Ilford, Greater London · established 2022
Frequently asked questions
How much does a self assessment accountant charge?▼
A standalone Self Assessment return typically costs £150–£350 per year. It is often bundled into monthly sole trader or director packages at about £10–£25 a month on our editorial benchmarks.
When is the Self Assessment deadline?▼
The online filing and payment deadline for the 2025/26 tax year is 31 January 2027. Paper filing is earlier. Confirm on GOV.UK if you are reading this after our 17 July 2026 review.
Do I need an accountant for Self Assessment?▼
No. File yourself if the return is simple and you will hit the deadline. Hire one if you have mixed income, property, capital gains, or you have filed late before.
What is the penalty for filing a tax return late?▼
The first late-filing penalty is £100. Further penalties can apply if the return remains outstanding and if tax is unpaid. Filing even when you cannot pay still matters.
Do company directors need Self Assessment?▼
Not solely because they are directors. A return may be needed for untaxed income; HMRC says dividends above £10,000 require Self Assessment, while tax on smaller amounts can sometimes be handled through a tax code. Check your own position with HMRC.
Will MTD replace the January Self Assessment deadline?▼
No. MTD adds quarterly digital updates for qualifying sole traders and landlords. You still make a final declaration after the tax year. The January payment date remains the one most people feel.
Sources
- GOV.UK — Self Assessment deadlines · checked 2026-07-17
- GOV.UK — Self Assessment tax returns · checked 2026-07-17
- GOV.UK — Making Tax Digital for Income Tax · checked 2026-07-17
- Pick My Accountant methodology · checked 2026-08-31
Information only — not tax, accountancy, or financial advice. Rules and thresholds change; confirm current positions with GOV.UK or a qualified accountant. Last updated 17 July 2026.