Who can do my Making Tax Digital quarterly updates for me as a plumber?

You, or an agent you authorise through HMRC: an accountant, bookkeeper or managed service. Homeowner jobs are outside CIS; work for a builder can be inside it. For 2027 joiners, the first update is due 7 August 2027.

Making Tax Digital for Income Tax (MTD) asks for four quarterly updates a year, sent from compatible software, then a tax return. For most plumbers and heating engineers the updates are built mainly from your own invoices, card takings and merchant receipts. This page follows GOV.UK as checked on 18 October 2026.

Your options as a plumber

Homeowner jobs and builder jobs

CIS 340 says private householders are not contractors, so a homeowner paying you direct for a boiler swap, a service or a new bathroom takes nothing off.

Work paid by a builder is different. CIS 340 says that if you do covered work for a contractor who is working for a householder, the contractor must operate CIS on what it pays you. HMRC lists fitting a bathroom or installing a whole heating system as covered. Its manual treats a boiler swap, an extra radiator, a repair or a service on its own as outside CIS, even when a builder pays you. If the same contract includes covered work, such as making good the wall, all of it comes within CIS. The CIS guide for plumbers has the full list.

Where deductions are taken, GOV.UK says your income is the pay before deductions, and the deductions are tax already paid. Once you are in MTD, HMRC adds the CIS deductions it holds to your tax return, and any refund is requested separately through HMRC online services. GOV.UK says a supporting agent cannot request repayments, so only you or your main agent can.

What a plumber's agent needs from you

• Your invoices and card takings from homeowners and landlords. If a card payout arrives with the fee taken off, GOV.UK says to find the full income and record it and the costs separately.
• Merchant receipts for boilers, pipe, fittings and parts, or a bank feed the agent can read.
• Monthly CIS statements from any builder that takes deductions.
• Van costs or a mileage log. On the cash basis, GOV.UK lists vans as allowable expenses. The other route is the flat rate: 55p a mile for the first 10,000 business miles in 2026-27, then 25p. It cannot be used for a van already claimed through capital allowances or deducted as a cost, and once you use it for a van, you keep using it for that van.
• Your 2024-25 and 2025-26 figures, to confirm your start date.

If your turnover is under £90,000, each item only needs to be marked as income or expense.

If you are near the VAT threshold

You must register for VAT if your taxable turnover for the last 12 months goes over £90,000, or if you expect it to go over £90,000 in the next 30 days alone. VAT returns then go through MTD-compatible software too, as a separate job from your income tax updates.

What any agent must have

• An HMRC agent services account. An agent needs one to sign clients up for MTD. HMRC now requires most people paid to deal with it about someone else's tax to register, through this account.
• Money-laundering supervision, by HMRC or a professional body.
• Your authorisation, not your password. The agent sends a request through HMRC, and you accept it within 21 days.

You can have one main agent and any number of supporting agents.

What this means for you

MTD started on 6 April 2026 if your qualifying income was over £50,000 in 2024-25. Otherwise it starts on 6 April 2027 if your 2025-26 qualifying income was over £30,000, or on 6 April 2028 if it was over £20,000 in 2026-27. Qualifying income is self-employed and property income before expenses. For a plumber that means every job, homeowner and builder alike, and in our reading CIS pay counts before deductions.

If you start in April 2027, your first update covers 6 April to 5 July 2027 (or 1 April to 30 June) and is due by 7 August 2027. If you have been in MTD since April 2026, your next update is due by 7 November 2026. GOV.UK says there are no penalty points for late updates in 2026-27. For 2027-28 they can start for April 2026 joiners, but the government said at the Budget on 28 October 2026 that April 2027 joiners get none until 2028-29 (earliest 7 August 2028), though updates must still be sent. Four points means a £200 penalty.

If you would rather hand it over, our Trades Tax plan is £35 a month including VAT. Your bank feed becomes your MTD quarterly updates, your CIS deductions are tracked all year, and you sign off every figure before anything reaches HMRC. The founding offer for the first 500 trades clients is £5 a month for your first 3 months, then £35 a month. Cancel any time. We'll remind you before it changes. Our VAT returns add-on is £10 a month including VAT. Our tax plans start once our HMRC registrations are complete. Until then you can join the waitlist, and no payment is taken.

Steps to hand over your updates

1. Use the free MTD check to confirm your start date, counting homeowner and builder work together.
2. Ask your current accountant whether it will send quarterly updates, and at what price, or compare MTD software for plumbers.
3. Ask whether it has an HMRC agent services account and money-laundering supervision.
4. Agree whether it will be your main agent, which includes the tax return and any CIS refund request.
5. Get the fee in writing, including VAT, and whether VAT returns are included.
6. Accept the authorisation request through HMRC, and send any CIS statements as they arrive.

There are more guides in the trades section.