What is the cheapest way to do a tax return as a sole trader?

The cheapest way is to file it yourself on HMRC's own online service, which HMRC's guidance calls free. Your 2025-26 return is due online by 11:59pm on 31 January 2027, and any tax is due the same day.

HMRC's guidance for agents lists it as the "HMRC free online service". To use it you must be registered for Self Assessment, and you need your Unique Taxpayer Reference (UTR) and sign-in details, which you can create when you first sign in. If you have filed before, GOV.UK says to check whether your account needs reactivating, or your return may be delayed. A few people cannot use it: GOV.UK lists partnerships, trusts and estates, non-residents living abroad, income from a trust, Lloyd's underwriters, religious ministers and gains on more than one asset as cases for commercial software or paper.

Free does not mean no effort. You still add up your income, expenses and any Construction Industry Scheme (CIS) deductions yourself. The paid options below either make that easier or take it off your hands.

Prices compared, October 2026

Each price is as the provider showed it on its own site on the date given, with VAT shown the way the provider shows it. Check what each one includes before you choose.

Our one-off tax return and tax plans are not open yet: they start once our HMRC registrations are complete. If you need your return done now, RIFT, Taxfix and the firms above are the better fit. Taxfix's full-service return was £99 for new customers on 15 October 2026, VAT not stated. Our one-off tax return costs £99, including VAT.

What drives the cost

• CIS deductions. Your gross pay and deductions have to match every monthly payment and deduction statement your contractors give you. More contractors means more statements to check.
• Expense records. A bank feed or a tidy spreadsheet is quick to work from. A bag of receipts takes longer, and paid services usually charge more for it.
• Property income. A rental property adds its own pages to the return. Sleek's fee guide puts a return with a second income source such as rent at £275 to £350 plus VAT, and says several rentals can push it past £400.

The cost of getting it wrong

A free return filed late is not free. For your 2025-26 return, GOV.UK lists these late filing penalties:

• £100 as soon as the return is late
• after 3 months, £10 a day, up to £900
• after 6 months, 5% of the tax due or £300, whichever is greater
• after 12 months, another 5% or £300, whichever is greater

Paying late brings penalties of 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest. If you have a reasonable excuse, you can appeal.

When paying someone can pay for itself

On CIS, contractors take 20% from registered subcontractors and 30% from those who are not registered, before you have worked out your real tax bill. Over-deducted CIS is claimed back through your tax return. The sooner after 5 April you file, the sooner HMRC can repay you.

You can claim it yourself on your own return; HMRC says you can claim a repayment directly through its free and secure service on GOV.UK. Paid CIS refund returns were listed at £354 including VAT by RIFT and £229 plus VAT by Baa Accounting on 16 October 2026. Paying makes sense if your statements are a muddle, you have several contractors, or a day spent on the return costs you a day's pay. If your records are simple, filing yourself keeps the whole refund.

What this means for you

If your records are tidy and you have one trade, file yourself on HMRC's service, which HMRC's guidance calls free. If you want an app to keep your records in order, the software prices above start at £64.99 a year including VAT. If you want someone else to do it, compare the one-off prices, add VAT where it is not included, and ask what happens if HMRC writes to you afterwards.

Whichever you choose, you stay responsible for the figures. Check them before anything goes to HMRC. GOV.UK also says voluntary and community organisations give free Self Assessment help.

Steps to do your return for the least money

1. Check you are registered for Self Assessment and have your UTR. First-timers must register before using the online service.
2. Gather your bank statements, receipts and every CIS payment and deduction statement for 6 April 2025 to 5 April 2026.
3. Sign in to HMRC's online service and fill in the self-employment pages, putting your pay before deductions as income and your CIS deductions in their own box.
4. If you get stuck, use GOV.UK's online help or a voluntary organisation before paying anyone.
5. Submit by 31 January 2027, earlier if you expect a CIS refund, and pay anything you owe by the same date.
6. Run the free MTD check to see whether Making Tax Digital starts for you on 6 April 2027. The trades section has more guides on CIS and tax returns.