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Making Tax Digital · Window & door fitters

Making Tax Digital for window and door fitters: do you need it?

170 days until it starts for sole traders over £30,000

Checked against GOV.UK, 14 October 2026.

The short answer for window and door fitters

A self-employed window fitter on a window company's books is paid through CIS, so the bank shows 80% of the real figure, and a fitter supplying direct is over £30,000 of turnover on a handful of houses. Over £30,000 for 2025 to 2026 means 6 April 2027.

The thresholds, from GOV.UK (26 March 2026): over £50,000 for 2024 to 2025 started on 6 April 2026, over £30,000 for 2025 to 2026 starts on 6 April 2027, over £20,000 for 2026 to 2027 starts on 6 April 2028. All counted as turnover, before expenses.

The figure HMRC checks

HMRC checks your qualifying income: everything that came in from self-employment and property, before expenses. GOV.UK calls it turnover. Wages from a PAYE job don't count.

The figure is what you invoiced, not what landed in the bank. GOV.UK says the deductions a contractor takes count as advance payments towards your tax and National Insurance bill, and qualifying income is counted before expenses, so the 20% that came off is still part of your turnover.

A worked year, in window and door fitters' numbers

A window fitter invoiced £42,000 in 2025 to 2026, fitting only for a window company that deducted £7,600 of CIS, plus a few private doors. Costs were £6,500: foam, sealant, fixings, trims and fuel. The bank shows £34,400. HMRC's figure is £42,000, so 6 April 2027.

Invoiced, before expenses
£42,000
Materials, costs, subbies
£6,500
CIS taken off by contractors
£7,600
What reached the bank
£34,400
HMRC's figure
£42,000

Making Tax Digital from 6 April 2027

Over £30,000 in the 2025 to 2026 tax year, so it starts on 6 April 2027. That tax year has ended, so the figure HMRC checks is the one on your 2025 to 2026 return. Only an amended return before 6 April 2027, or all your trade and property income stopping, changes it, and a short first year gets scaled up to 12 months (GOV.UK, qualifying income, 11 September 2026).

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CIS and window and door fitters

Fitting windows and doors is alterations to a building, so a window company or a builder paying you to fit deducts 20% from the labour. Homeowners paying you direct don't. If you supply the frames as well, the whole price is your Making Tax Digital turnover.

The rate, from GOV.UK: 20% if you're registered for CIS, 30% if you're not, nothing if you have gross payment status. Whoever deducts must give you a statement, and that statement is your proof.

Work out a CIS deduction, free

The records window and door fitters lose

  • Fitting paid per frame on the company's weekly statement, net of CIS.
  • Foam, silicone and packers bought on your card when the delivery was short.
  • A composite door supplied direct for a neighbour, income and expense both, written nowhere.

Every three months your software sends HMRC totals for each income and expense category, not the receipts themselves. The updates are due on 7 August, 7 November, 7 February and 7 May, and each one covers the tax year so far.

InstaQuote holds those quotes, invoices and expenses as you work, so they can go into your Making Tax Digital software as the digital records. It isn't that software itself. ANNA, our partner, is the software your updates and return go to HMRC through.

Questions window and door fitters ask

The window company deducts 20%. Is my turnover before or after?

Before. GOV.UK counts qualifying income before expenses, and the CIS deduction is tax paid in advance, not an expense. Record the gross fitting fee and the deduction together.

If I supply and fit, is the frame my turnover?

Yes, when the customer paid you for it. The frame price is turnover and what you paid the fabricator is an expense. Fitting only, the frame never touches your books.

FENSA registration, insurance, the van: where do they go?

Into your expense totals. The quarterly update carries a total for each expense category, so each cost needs recording against the right category when you pay it, not found in April.

The window company is a PAYE employer for some lads and pays me as a subbie. Which am I?

If they pay you gross or with CIS taken off against your invoices, you're self-employed and that money is qualifying income. If they put you on payroll with tax deducted as PAYE, it's wages and GOV.UK leaves it out of the threshold.

When would my first quarterly update be?

If you start in April 2027, by 7 August 2027 for 6 April to 5 July. Then 7 November, 7 February and 7 May, each covering the year so far. GOV.UK lets you send updates more often if you want.

What records does HMRC actually want from a window fitter?

A digital record of each income and expense with its amount, date and category, in the same categories as Self Assessment, and the original invoice or receipt kept or copied. The fitting statement, the foam and the fuel are three entries, not a shoebox.

Does InstaQuote file my Making Tax Digital updates?

No. InstaQuote holds the quotes, invoices and expenses so they can go into your Making Tax Digital software as the digital records; it isn't that software itself. ANNA, our partner, is the software your updates and return go to HMRC through, from the business account you open inside your InstaQuote account.

Checked against GOV.UK

Built on the tools, not in a boardroom

Tom, plaster still on his top, shaking a customer's hand in front of his van

I'm Tom. Ten years in the trade, and every quote done sat in the van on the drive. If that's you, keep reading.

Tom · Founder · InstaQuote Ltd

I started in the trade at 17. Ten years in, the work was fine. It was everything after the work.

Every night I'd pull up at home and sit in the van on the drive, because the quotes and the invoices and the chasing had to be done before I went in. Every night. And the better the quotes were, the more people rang, so it never got smaller. I was starting to hate a trade I'd loved since I was 17.

If you've ever sat outside your own house doing paperwork, you know.

I tried every system going. Every one made a quote, then left me in the van doing the rest.

So I came off the tools and spent 18 months building the thing that didn't exist. Every step I used to do on that drive, built in so it happens without you. The quote prices itself from your rates. The deposit books the job. The invoice goes when you tap Job done. The late payer gets chased. VAT and CIS worked out.

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