Choosing a trusted online tax accountant in the UK is mostly about knowing what is included in the fee. After many years in practice, I've seen the same pattern: people compare headline prices and later discover that bookkeeping, VAT returns or HMRC correspondence were never part of the quote.

Online firms are now a mainstream option for sole traders, landlords and small companies. Most work with fixed monthly or annual fees, secure portals and cloud software, so a fee is easier to predict than with a traditional high street practice. The figures below are indicative market ranges for 2026/27 and vary by firm.

Sole traders and Self Assessment

A basic Self Assessment return for a sole trader with straightforward income typically costs £150 to £350 online. If you also want bookkeeping and year-round support, expect £40 to £120 a month. The deadlines remain 31 October for paper returns and 31 January for online returns and payment of tax.

Landlords

Rental income is reported on the UK property pages of the return. Online accountants usually charge £150 to £400, depending on the number of properties, whether you hold them jointly, and whether mortgage interest is claimed under the Section 24 rules (a 20% tax reduction rather than a deduction from rent).

Limited companies

Annual accounts, a corporation tax return (CT600) and a confirmation statement usually cost £600 to £1,500 a year, or £50 to £150 a month in packages. Corporation tax is 19% on profits up to £50,000, 25% above £250,000, with marginal relief in between.

Typical fee ranges

What pushes the price up

• Messy or missing records that need reconstructing

• Multiple income streams, such as employment, dividends and rental income

• Capital gains on shares or property

• Overseas income or residence questions

• Filing late returns for earlier tax years

Why the cheapest quote can cost more

A low fee often covers only data entry, with no tax planning. Missing a claim like the £1,000 trading allowance, or failing to use your £12,570 Personal Allowance efficiently, can cost far more than a higher fee would have.

Services, Rules and Real Scenarios

Fees make sense only when you know what drives the workload. Much of it comes from rules that have changed recently, so a good accountant should explain what applies to you.

Making Tax Digital for Income Tax

From 6 April 2026, sole traders and landlords with qualifying income above £50,000 must keep digital records and send quarterly updates to HMRC through compatible software. The threshold drops to £30,000 from April 2027 and £20,000 from April 2028. Accountants increasingly charge for these quarterly submissions, often £30 to £75 a quarter, so ask whether they are included.

VAT and payroll

The VAT registration threshold is £90,000 of taxable turnover. If you cross it, you must register within 30 days. Payroll fees cover Real Time Information submissions, auto-enrolment, and year-end documents such as the P60 and P45 (the P11D covers benefits in kind).

Example: a freelance designer

Sarah earns £62,000 in self-employment with £8,000 of allowable expenses, so her profit is £54,000. Income tax at 20% applies to the £41,430 of profit above her £12,570 allowance, up to the £50,270 higher-rate threshold, with 40% on the remainder, plus Class 4 National Insurance. An online accountant charging £300 a year who spots £1,200 of missed home-office and mileage claims saves her roughly £500 to £600 in tax and NI, so the fee more than pays for itself.

Example: a landlord with two properties

David lets two flats with £24,000 of annual rent and £9,000 of expenses. His accountant restricts finance costs correctly and checks his payments on account. Without that, he risked overpaying and facing a surprise January bill.

Example: a new limited company director

Priya takes a salary of £12,570 and dividends. Her accountant balances salary and dividends against the dividend allowance, now £500, and the 8.75% basic-rate dividend tax rate. The gain from this planning dwarfs the £90 monthly fee.

How to check an accountant is trustworthy

• They are a member of a recognised body such as ICAEW, ACCA, AAT, CIOT or ATT

• They hold professional indemnity insurance

• They are registered with HMRC for anti-money laundering supervision

• They give a written engagement letter showing what is and is not included

You can also check authorisation to act on your behalf through HMRC's agent services.

Choosing, Comparing and Getting Value

Once you know the price bands, the real task is matching a firm to your circumstances.

Fixed fee versus hourly rates

Fixed fees suit predictable work. Hourly rates, typically £80 to £200, suit one-off problems such as an HMRC enquiry. Ask what happens if your circumstances change mid-year.

Questions worth asking before you sign

Ask who will deal with your file, how quickly they respond, and whether HMRC letters and penalty appeals are covered. A good firm answers plainly, without jargon.

Hidden extras to watch for

Some firms charge separately for software, extra bank feeds, registering for VAT, or year-end payroll filing. Request an itemised quote so you can compare like with like.

Preparing your records

Keep invoices, receipts and bank statements organised for at least five years after the 31 January filing deadline (six years for company records). Tidy records reduce your accountant's time and your bill.

Late filing and penalties

A late Self Assessment return starts at £100, even if no tax is due, with further penalties and interest the longer it runs. Using an accountant who diarises deadlines is often the cheapest protection.

Conclusion

A trusted online tax accountant in the UK should cost what the work genuinely requires, not simply the lowest price on a comparison page. For most sole traders, landlords and small companies, a fair fee buys accuracy, compliance with HMRC rules and, frequently, a tax saving larger than the bill. Compare scope as carefully as price, confirm credentials, and choose someone who explains your position clearly. Rates and thresholds change each tax year, so check current figures on GOV.UK or with your adviser.