One 2026 fee guide puts a sole trader's tax return at £200 to £350 plus VAT. Most gas work for householders is outside CIS, so VAT, card takings and parts usually shape the price more than CIS does.
There is no official price list. The figures below come from firms' own fee guides and price pages, and from ByteStart, a publisher that works with partner firms, all checked on 18 October 2026. They have a commercial interest, so treat them as the going rate, not a quote.
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What gas engineers are quoted
| Source and date | What it covers | Price as published | Including VAT at 20% |
|---|---|---|---|
| Sleek fee guide, updated 11 September 2026 | Sole trader return | £200 to £350 + VAT | £240 to £420 |
| Accotax fee guide, 17 August 2026 | Basic return: one or two income sources, organised information | £150 to £300 + VAT | £180 to £360 |
| Accotax fee guide, 17 August 2026 | Freelancer or contractor return; CIS named as a price factor | £200 to £500 + VAT | £240 to £600 |
| ByteStart cost guide, updated 25 September 2026 | One-off return | £150 to £300, VAT not stated | Not stated |
| ByteStart cost guide | Monthly package with VAT and support | £50 to £100+ a month, VAT not stated | Not stated |
| Gorilla Accounting, MTD Comply, checked 18 October 2026 | Software, quarterly updates and the tax return; listed as ideal for non-VAT registered businesses | From £49 + VAT, sold as a fixed monthly fee | From £58.80 a month |
| Gorilla Accounting, MTD Complete, checked 18 October 2026 | Adds year-end accounts and VAT returns; listed as ideal for VAT-registered businesses | From £79 + VAT, sold as a fixed monthly fee | From £94.80 a month |
Sleek says a single self-employed income stream with clean bookkeeping usually lands around £200 to £250, and that using cloud accounting software all year pulls the fee down by £50 to £100.
What drives the price for a gas engineer
| What you have | Why it adds work |
|---|---|
| Boiler swaps, servicing and repairs | For a householder paying direct there is no CIS, because CIS 340 says private householders are not contractors. HMRC's manual says replacing a central heating boiler is not installing a system of heating, and CIS 340 excludes servicing, so on their own they are outside CIS. |
| Heating installs for a builder or developer | Installing a complete heating system, or a mains gas supply, for a contractor is CIS work. A contractor that takes a deduction must give you a statement within 14 days of the end of each tax month. |
| Card takings | A card payout may arrive with the fee taken off. Where you only know income after costs, GOV.UK says to find the full amount and record the income and the costs separately. |
| Boilers and parts you supply | Taxable turnover is everything you sell that is not exempt or out of scope, so in our reading the boilers and parts you charge for count towards the £90,000 VAT threshold as well as your labour. |
| VAT registration | Once taxable turnover for the last 12 months goes over £90,000, or you expect it to in the next 30 days alone, you must register, and a VAT Return is usually due every 3 months. |
| Making Tax Digital | Over £50,000 of qualifying income (income before costs) in 2024-25 meant starting on 6 April 2026; over £30,000 in 2025-26 means 6 April 2027; over £20,000 in 2026-27 means 6 April 2028. Quarterly updates are then due every 3 months for each business. |
| Untidy records or late years | Sleek says disorganised records or missing receipts add £100 to £300, and puts each missed year at £150 to £400 plus VAT. |
Which heating jobs are inside CIS is set out in does CIS apply to plumbers and heating engineers.
Fixed fee or a share of your refund
If all your work is for householders, no CIS deductions are taken, so there is no CIS refund to share. If a developer does take deductions, GOV.UK says you record pay before deductions as income and the deductions as CIS deductions on your tax return, and HMRC pays back any refund due. Once you are in Making Tax Digital, you cannot claim the refund in the MTD tax return itself; it is requested separately. GOV.UK says you do not need an agent to claim a tax refund. Our CIS refund companies comparison lists dated, fixed fees.
Can you claim the fee back?
Partly. GOV.UK says accountancy fees can be allowable when you hire an accountant only for business reasons, but you cannot claim the cost of preparing and submitting your Self Assessment tax return. HMRC's manual allows the normal recurring cost of preparing your business accounts. It says the cost of completing a tax return is not allowable, though the extra personal cost is likely to be minimal if your other tax affairs are straightforward. In our reading, if one fee covers both, only the business accounts part counts.
Gas Safe registration is separate. The Gas Safety (Installation and Use) Regulations 1998 say a self-employed person must not work on a gas fitting or service pipework unless they belong to a class of persons approved by the Health and Safety Executive. GOV.UK allows trade body or professional organisation membership related to your business, but does not name Gas Safe; the gas engineer expenses guide covers it with your other costs.
What this means for you
In our reading, if you mostly fit, service and repair boilers for householders, are not VAT registered and keep card payouts and merchant receipts in software through the year, a fee near the bottom of the ranges above is realistic. If you are VAT registered, also install systems for developers under CIS, or have years to catch up, expect the upper end or a monthly package that includes VAT returns. Either way, the figures on your return are your responsibility.
Steps to get a fair price
- Use the free MTD check to see whether and when MTD starts for you.
- Note whether you are VAT registered, or how close boilers, parts and labour together bring you to £90,000.
- Split last year's work into householder jobs and installs paid by contractors, and gather any CIS statements.
- Download your card provider's statements, which show full takings and fees.
- Ask at least two firms for a written yearly price in pounds, including VAT, that says whether VAT returns and quarterly updates are covered.
For software, see the best MTD software for gas engineers and how to sign up for MTD as a gas engineer. The trades section has more guides.
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Questions people ask
How much does an accountant charge a gas engineer for a tax return?
Sleek's 2026 fee guide puts a sole trader return at £200 to £350 plus VAT, which is £240 to £420 with VAT at 20%. Accotax puts a freelancer or contractor return at £200 to £500 plus VAT. These are firms' own figures, not an independent survey.
Does CIS apply to boiler installs and servicing?
Not for a householder paying you direct, because CIS 340 says private householders are not contractors. Even when a contractor pays, HMRC's manual says replacing a central heating boiler, adding a radiator or a repair is not installing a system, and CIS 340 excludes servicing, so on their own they are outside CIS. A repair contract that includes making good to the building is caught. Installing a complete heating system for a contractor, or replacing a whole one, is inside.
Will being VAT registered make my accountant cost more?
It usually adds work. GOV.UK says you usually send a VAT Return every 3 months. Gorilla Accounting puts VAT returns in its higher MTD Complete package, not in its entry one.
Can I claim my accountant's fee as a business expense?
Partly. GOV.UK says accountancy fees can be allowable when you hire an accountant only for business reasons, but you cannot claim the cost of preparing and submitting your Self Assessment tax return. HMRC's manual allows the normal recurring cost of preparing your business accounts, but not the cost of completing a tax return.
Is my Gas Safe registration an allowable expense?
GOV.UK lists trade body or professional organisation membership as allowable if it is related to your business, but it does not name Gas Safe. The law says a self-employed person must not work on a gas fitting or service pipework unless they belong to a class of persons approved by HSE. In our reading, a registration you need to meet that rule is paid only for the business.
Sources
- CISR14090: The Scheme: construction operations: building service systems (HMRC manual, checked 18 October 2026)
- Construction Industry Scheme: a guide for contractors and subcontractors (CIS 340), sections 2.3, C.2 and C.3 (GOV.UK, checked 18 October 2026)
- What you must do as a CIS subcontractor: Get paid (GOV.UK, checked 18 October 2026)
- What you must do as a CIS subcontractor: Pay tax and claim back deductions (GOV.UK, checked 18 October 2026)
- Use Making Tax Digital for Income Tax: Create digital records (GOV.UK, checked 18 October 2026)
- Use Making Tax Digital for Income Tax: Submit your tax return (GOV.UK, checked 18 October 2026)
- Find out if and when you need to use Making Tax Digital for Income Tax (GOV.UK, checked 18 October 2026)
- Use Making Tax Digital for Income Tax: Send quarterly updates (GOV.UK, checked 18 October 2026)
- Register for VAT: When to register (GOV.UK, checked 18 October 2026)
- Submit a VAT Return (GOV.UK, checked 18 October 2026)
- Expenses if you're self-employed: Legal and financial costs (GOV.UK, checked 18 October 2026)
- Expenses if you're self-employed: Subscriptions (GOV.UK, checked 18 October 2026)
- BIM46450: Professional fees, taxation account and negotiations (HMRC manual, checked 18 October 2026)
- The Gas Safety (Installation and Use) Regulations 1998, regulation 3 (legislation.gov.uk, checked 18 October 2026)
- How to choose a tax agent (GOV.UK, checked 18 October 2026)
- Accotax: How much do accountants charge for tax returns in the UK? (17 August 2026, checked 18 October 2026)
- Sleek: How much do accountants charge for Self Assessment in 2026? (updated 11 September 2026, checked 18 October 2026)
- ByteStart: How much should you pay for an accountant if you're self-employed? (updated 25 September 2026, checked 18 October 2026)
- Gorilla Accounting: MTD packages (checked 18 October 2026)
This is general information to help you understand the rules. It isn't tailored to your circumstances, so check your own position before acting on it.
Righto Tax is a trading name of NJG Consultancy Ltd, registered in England and Wales, company number 16095900. Registered office: Jubilee House, East Beach, Lytham St Annes, FY8 5FT.
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