How do I sign up for Making Tax Digital for Income Tax as a gas engineer?

Sign up on GOV.UK with your Self Assessment sign-in. If your turnover before CIS deductions, plus rent, was over £30,000 in 2025-26, you start on 6 April 2027 (over £50,000 in 2024-25: already started).

Making Tax Digital for Income Tax (MTD) works the same for a gas engineer as for any sole trader. What differs is the mix of customers: homeowners, landlords and letting agents, boiler-cover firms, and heating contractors who may take Construction Industry Scheme (CIS) deductions. This page follows GOV.UK and HMRC guidance, checked on 18 October 2026.

Do you need to sign up, and when

HMRC tests your qualifying income: all your self-employment and property income before expenses, also called turnover. Wages and dividends do not count.

HMRC writes to people over the line, but GOV.UK says checking is your responsibility.

Adding up a gas engineer's turnover

CIS 340 says private householders are not contractors. It includes installing heating systems, power supply systems and gas mains, and excludes the repair, servicing and maintenance of heating and power supply systems. HMRC's CIS manual counts gas as a power supply and says replacing even a central heating boiler is not installing a system. The catch is CIS 340's rule that if you install a system for a contractor who is working for a householder, the contractor must still operate CIS on what they pay you. A contract that also includes building work, such as making good, is all caught. The CIS guide for heating engineers has the job-by-job list.

Under the Gas Safety Regulations, landlords must have each gas appliance and flue they are responsible for checked at least every 12 months. In our reading, that check is servicing, outside CIS.

Take a gas engineer, registered for CIS, under £50,000 in 2024-25. In 2025-26, homeowners paid £12,000, letting agents £4,500 for safety checks, and a boiler-cover firm £6,000 for repairs. A heating contractor's statements show £9,000 gross, labour only, for complete installs. The 20% deduction was £1,800, so £7,200 reached the bank. Bank receipts total £29,700, under £30,000. But qualifying income is £31,500, so MTD starts on 6 April 2027.

What the sign-up asks

You must be registered for Self Assessment and have sent a tax return in the last 2 years. GOV.UK then asks for your business name (the name on your invoices), address and trade, your start date if it was in the last 2 tax years, the tax year you will start, and every self-employment and property source, including any that has stopped since your last return. The list does not include Gas Safe: the legal duty to belong to a class approved by the Health and Safety Executive before doing gas work is a safety rule, separate from tax.

GOV.UK treats each trade as a separate business. In our reading, boiler work, safety checks and installs are one trade.

You sign in with the user ID and password you got when you registered for Self Assessment. You may be asked to prove your identity with a phone app and your passport or driving licence. On 13 October 2026 GOV.UK removed the option to answer questions instead.

Choosing software first

GOV.UK says to choose software before you sign up. HMRC's software finder listed 159 products for sole traders and landlords on 18 October 2026, and HMRC recommends none. Each listing shows whether it sends quarterly updates only or the tax return too, and each product page whether CIS and PAYE employment are Ready now, In development or Not included. In our reading, if you do CIS work or have a PAYE job, pick one showing those items as Ready now.

What this means for you

If your turnover, plus any rent, was over £30,000 in 2025-26 but not over £50,000 in 2024-25, you start on 6 April 2027. The year before you start still gets a normal Self Assessment return. Volunteer now for 2026-27 and that year's return goes through MTD software instead.

GOV.UK says there are no penalty points for late quarterly updates in 2026-27. The 28 October 2026 Budget said April 2027 joiners get none for 2027-28 updates either, though updates must still be sent, so the earliest possible point is 7 August 2028. After that, each missed deadline earns a point, and 4 points brings a £200 penalty. Volunteers get no points for late updates, but 2 points for late returns brings £200. HMRC adds your CIS deductions to your MTD tax return, and any refund is requested separately through HMRC online services.

An agent with an HMRC agent services account can sign you up once you authorise them, using your full name, date of birth, National Insurance number and business details. Of your agents, only a main agent can submit your tax return.

Steps to sign up as a gas engineer

1. Add up your 2025-26 income: every job, gross CIS pay and any rent. If your trade or property business started or stopped part-way through, see GOV.UK's annualising rules first. The free MTD check shows your start date.
2. Check you are registered for Self Assessment and have filed a return in the last 2 years.
3. Choose MTD software that handles CIS if you need it, or someone to do it.
4. Have your business name, address, trade and any recent start date to hand.
5. Sign in to the GOV.UK sign-up service, add every business and property, and pick your start year.
6. Complete any identity check, or authorise your agent and let them sign you up.
7. Keep every monthly CIS statement, and record each payment as it arrives.

See gas engineer expenses and the trades section for more.