Costs & fees
How much does self assessment cost with an accountant?
By Kaiser Khan · Updated 17 July 2026
What the fee covers
A self assessment fee normally covers gathering your figures, preparing and submitting the return to HMRC, telling you what to pay and when, and handling straightforward queries. Better firms also review your allowable expenses and flag reliefs you may have missed — that review is often where the fee earns itself back.
What makes a return cost more
A simple employment-plus-a-bit-of-freelance return sits at the bottom of the range. Buy-to-let properties, dividend and investment income, capital gains, foreign income, or self-employment with messy records each add schedules and time. Multiple income types can push a one-off fee towards £600.
One-off return or monthly package?
If you are a director or landlord with otherwise simple affairs, a one-off return each January is usually the cheapest route. Sole traders trading through the year often do better on a £39–£89 monthly package that bundles the return with record-keeping support — and, from 6 April 2026, Making Tax Digital quarterly updates for qualifying income over £50,000.
Do not leave it until January
The online filing deadline is 31 January 2027 for the 2025/26 tax year. Accountants raise prices or turn work away in the January rush, and late filing triggers an automatic £100 penalty. Sending records over in autumn gets you a calmer service and a better fee.
People also ask
Can I file self assessment myself for free?
Yes — HMRC's online service costs nothing. You are trading the fee for your own time and the risk of missed expenses or errors. If your affairs are simple, DIY is reasonable; if you have property, dividends or a business, professional help usually pays for itself.
Is the self assessment fee tax-deductible?
For sole traders, the part of the fee that relates to your business is normally an allowable expense. Fees for purely personal tax matters may not qualify — your accountant can confirm the split.
What happens if I miss the deadline?
An immediate £100 penalty applies even if you owe no tax. After three months, daily £10 penalties can add up to £900, with further charges at six and twelve months — plus interest and late-payment penalties on any tax owed.
This article is general information for UK businesses, not tax, legal, or financial advice, and thresholds change — confirm current rules on GOV.UK or with a qualified accountant before acting. Fee figures are indicative benchmarks from ourmethodology.