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20%, 5% or zero: rating building work

The single most common mis-rating in the trades is treating an extension as if it were new build. The rate depends on what the work does to the building rather than what the trade is, so the same electrician can be zero-rated on one site, on 5% on the next and on 20% on the third. There is also a hard, dated cliff edge coming on energy-saving materials — 1 April 2027 — that is worth pricing for now.

Guide · Updated August 2026

Registration first: £90,000 and the two looks

ItemFigureApplies from
Registration threshold£90,0001 April 2024
Deregistration threshold£88,0001 April 2024

Both were confirmed unchanged for 2025-26 and 2026-27 at Budget 2025.

There are two separate tests and trades usually only know about the first.

The backward look: register if taxable turnover in the last twelve months — rolling, not your accounting year — exceeds £90,000. Notify within 30 days of the end of the month in which you crossed it. Registration takes effect from the first day of the second month after crossing.

The forward look: register if you expect taxable turnover to exceed £90,000 in the next 30 days alone. Notify by the end of that 30-day period, and registration is effective from the date you realised. This is the one that catches a trade winning a single large contract — one £100,000 job with a 30-day programme triggers registration immediately, regardless of the previous twelve months.

Zero rate: new dwellings, and the four conditions

Construction of a building designed as a dwelling or number of dwellings, a building for a relevant residential purpose, or one for a relevant charitable purpose, is zero-rated under VAT Notice 708. The supply must be made in the course of construction, before completion, and by a person with "person constructing" status.

"Designed as a dwelling" has four conditions, and all four must hold:

  1. Self-contained living accommodation
  2. No direct internal access to any other dwelling
  3. Construction in accordance with statutory planning consent
  4. No prohibition on separate use or disposal

The fourth is the trap, and it catches annexes constantly. A granny annexe built with a planning condition preventing it from being sold or let separately from the main house fails condition four — so it is standard rated at 20%, not zero. The client who was quoted with no VAT is then £14,000 short on a £70,000 job, and the argument about who absorbs it is not one anybody wins.

Materials supplied with zero-rated or reduced-rated work take the same rate as the services. That is generous and it is worth understanding: on a genuine new-build, the materials you supply and install go out at 0% too.

The builders' block — what stays at 20% even on a new build

Non-qualifying goods remain standard rated regardless of the rate on the rest of the job:

  • Fitted furniture
  • Carpets
  • Separately hired plant or scaffolding

The scaffolding point is a live issue on new-build sites. Scaffolding erection as a service follows the rate of the construction work; scaffolding hired separately is standard rated. Scaffolders invoicing a mix of erection, hire period and dismantle on one zero-rated site need the invoice to reflect that split honestly, and it is worth agreeing with the main contractor in writing before the first application for payment rather than after.

The 5% rate: three routes, and what does not qualify

  • Changed number of dwellings conversion — converting premises so the number of single household dwellings differs from before, up or down. A house to two flats qualifies; two flats back to a house qualifies. Mere refurbishment of existing units does not.
  • Non-residential to residential conversion — premises never previously used residentially, or not used residentially for ten years or more. Barns, offices, shops and pubs are the usual candidates.
  • Renovation of a dwelling empty for two years or more — evidenced by Electoral Roll data, Council Tax records, or a certificate from the local authority's Empty Property Officer.

The evidence requirement on the third route is where jobs go wrong. A verbal assurance from the client that the house "has been empty for years" is not evidence. Get the Empty Property Officer letter or the Council Tax record before you price at 5%, because if it turns out the property was occupied eighteen months ago, the 15-point difference is yours to find.

Standard rate: repairs, maintenance and — the big one — extensions

Twenty per cent applies to repairs, maintenance, extensions and alterations to existing occupied dwellings, plus architects' and surveyors' services and separately hired plant and scaffolding.

The extension point deserves its own sentence. An extension to an existing occupied house is standard rated, however new the structure is and however much it looks like new build from the scaffold. This is the single most common mis-rating in the sector. New build means a new building; adding to an existing one is an alteration.

Worked example — three jobs, one trade

A builder prices three jobs in the same month, each £80,000 of work and materials:

  • Two new houses on a plot. Designed as dwellings, planning consent, no internal access to another dwelling, no prohibition on separate disposal. Zero-rated. VAT charged: £0.
  • A barn conversion, never used residentially. 5%. VAT charged: £4,000.
  • A rear extension to an occupied semi. 20%. VAT charged: £16,000.

Three identical-looking invoices, £16,000 of difference. Quote the third as if it were the first and you have priced a £16,000 hole into the job. Where the customer is a VAT-registered contractor rather than a householder, the standard-rated job also goes onto the reverse charge — while the zero-rated one does not.

Energy-saving materials, and the 1 April 2027 cliff

The installation of energy-saving materials in residential accommodation is zero-rated from 1 May 2023 to 31 March 2027. From 1 April 2027 it reverts to the 5% reduced rate.

That is a hard, dated cliff edge and it is the most time-sensitive VAT item facing the trades. A job that straddles it changes rate mid-programme. If you install heat pumps, solar or insulation, the contracts you are signing now for delivery in spring 2027 need to say which rate applies and what happens if the work slips past 31 March.

Qualifying materials: controls for central heating and hot water systems; draught stripping; insulation; solar panels; wind turbines; water turbines; ground source heat pumps; air source heat pumps; micro combined heat and power units; wood-fuelled boilers. Added 1 February 2024: water source heat pumps; batteries for storing electricity; smart diverters; and groundworks for ground or water source heat pump pipework. From the same date the relief also covers buildings used solely for a relevant charitable purpose.

One restriction that catches merchants and installers who also sell over the counter: the relief applies only where the materials are installed. Supply-only is standard rated.

The Flat Rate Scheme: the rate is set by materials, not by trade

ItemFigure
Joining thresholdTaxable turnover excluding VAT £150,000 or less in the next year
Leaving thresholdTotal income including VAT over £230,000 in a year, or expected in the next 30 days alone
First-year discount1% off the sector rate for 12 months after VAT registration
Limited cost business rate16.5%
Limited cost business testRelevant goods under 2% of flat rate turnover, or over 2% but under £1,000 a year

The two construction sector rates:

SectorRate
Building or construction services — labour only (materials under 10% of turnover)14.5%
General building or construction services (materials 10% or more)9.5%

Both categories cover electricians, plumbers, joiners, carpenters, painters, plasterers and roofers. The rate is set by the materials proportion, not by the trade. A plumber supplying his own boilers is on 9.5%; the same plumber on labour-only subcontract work is on 14.5%.

The structural point for a CIS subcontractor is that the scheme has largely stopped working. A labour-only subcontractor whose sales are all reverse-charged has, in effect, no VAT-inclusive turnover to apply a flat rate to, and its relevant goods spend is low by definition — so the limited cost business rate of 16.5% looms as well. The Flat Rate Scheme remains genuinely useful for a trade selling direct to domestic customers, outside CIS and outside the reverse charge. If you went onto it before March 2021 and your work is now mostly subcontract, it is worth a review.

How to get this right on site

  1. Rate the job before you quote it, not when you invoice. The rate is a pricing input.
  2. Ask what the work does to the building: new building, changed number of dwellings, non-residential for ten years, empty for two years, or none of those.
  3. Get the evidence in writing for 5% and zero cases — planning consent, Empty Property Officer certificate, Council Tax history.
  4. Check the separate-disposal condition on any annexe. It is the most common zero-rating failure we see.
  5. Then, and only then, ask the reverse charge question — because it only applies to standard and reduced-rated work. The reverse charge checker runs that step, and accounts and tax covers how this lands in the returns.

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Quick answers

Frequently asked

Is an extension zero-rated like a new build?

No. An extension or alteration to an existing occupied dwelling is standard rated at 20%, however new the structure is and however much it looks like new build on site. Zero-rating applies to the construction of a new building designed as a dwelling, a building for a relevant residential purpose, or one for a relevant charitable purpose — and adding to an existing building is an alteration rather than a new building. This is the single most common mis-rating in the trades. On an £80,000 extension quoted as if it were new build, the missing VAT is £16,000, and there is rarely a good outcome to that conversation with a householder after the fact.

Can I zero-rate a granny annexe?

Usually not. Zero-rating requires the building to be designed as a dwelling, and that has four conditions: self-contained living accommodation, no direct internal access to any other dwelling, construction in accordance with statutory planning consent, and no prohibition on separate use or disposal. Annexes very often fail the last one, because planning consent commonly prevents the annexe being sold or let separately from the main house. Where that prohibition exists the annexe is standard rated at 20%. Read the planning consent before you price the job, because the condition is usually there in writing and it decides a fifth of the contract value.

When does the 5% rate apply to building work?

There are three routes. A changed number of dwellings conversion, where the number of single household dwellings after the work differs from before — up or down — so a house into two flats qualifies but refurbishing existing units does not. A non-residential to residential conversion, where the premises were never used residentially or have not been for ten years or more, which covers barns, offices, shops and pubs. And the renovation of a dwelling that has been empty for two years or more, evidenced by Electoral Roll data, Council Tax records or a certificate from the local authority's Empty Property Officer. Get that evidence before pricing at 5%.

What happens to the zero rate on heat pumps and solar in 2027?

It ends. The installation of energy-saving materials in residential accommodation is zero-rated from 1 May 2023 to 31 March 2027, and from 1 April 2027 it reverts to the 5% reduced rate. That is a hard dated cliff edge, and it is the most time-sensitive VAT item facing the trades right now. If you install heat pumps, solar panels, insulation or battery storage, any contract you sign now for delivery in spring 2027 should state which rate applies and what happens if the programme slips past 31 March. Note also that the relief only covers materials that are installed — supply-only sales are standard rated either way.

Is the VAT Flat Rate Scheme still worth it for a subcontractor?

Usually not. The two construction sector rates are 14.5% for labour-only services where materials are under 10% of turnover, and 9.5% for general building services where materials are 10% or more, with the rate set by the materials proportion rather than by the trade. But a labour-only subcontractor whose sales all fall under the VAT domestic reverse charge has almost no VAT-inclusive turnover to apply a flat rate to, and low relevant goods spend also risks the 16.5% limited cost business rate. The scheme remains genuinely useful for a trade selling direct to domestic customers, outside CIS and outside the reverse charge.

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