Building an extension on an existing Rugby house is normally charged at 20 per cent VAT, so a £50,000 quotation that leaves VAT out becomes £60,000 on the bill. That single line is the commonest gap between two quotations that look alike, and it is why the VAT wording matters more than most homeowners expect. HMRC allows a 0 per cent rate for a new dwelling built within an extension and a 5 per cent rate in a few narrower cases, but most household extensions meet neither. This guide sets out what applies, which exceptions exist, what to ask a builder to show and how to compare quotations. It is not tax advice or a Belmax price.
The short answer
Price the extension with VAT shown
For an extension to an existing home in Rugby, HMRC says the standard rate of 20 per cent normally applies to labour and fitted materials. A 0 per cent rate needs a new dwelling wholly within the extension, and 5 per cent needs a long-empty home or a conversion. Ask each builder to show VAT as a separate line.
The standard rate is where an extension starts
GOV.UK says most work on houses is charged at 20 per cent VAT, and HMRC's Notice 708 says work to an existing building will normally be standard rated.
If you are adding a kitchen, a bedroom or a family room to a house you already live in, in Rugby or anywhere else in England, the working assumption is 20 per cent on the builder's labour and on the materials the builder fits. GOV.UK's guidance for builders says most work on houses and flats by builders and similar trades is charged at the standard rate of 20 per cent. It does not name extensions, so it sends readers to HMRC's Notice 708 on buildings and construction, which was last updated on 26 August 2026. That notice says: "If you carry out work to an existing building, you will normally have to charge VAT at the standard rate."
The Federation of Master Builders, in a guide dated 4 March 2026, puts it plainly: home extensions attract 20 per cent VAT on labour and materials. It also tells homeowners to always confirm whether quotes are inclusive or exclusive of VAT. That second sentence matters more than the first, because the rate is rarely in doubt but the wording on a quotation often is.
The arithmetic is simple and worth doing before you compare anything. A quotation of £50,000 that excludes VAT becomes £60,000 once 20 per cent is added. A quotation of £60,000 that includes VAT is the same money as £50,000 plus VAT. These figures are arithmetic only, not a Belmax price and not a market range.
Check the guidance: GOV.UK: VAT for builders, houses and flats, HMRC: Buildings and construction (VAT Notice 708), FMB: single storey extension costs, a practical guide for homeowners.
Which rate applies: 20, 5 or 0 per cent
Zero rating needs a new dwelling wholly inside the extension, and 5 per cent needs a conversion or a home empty for two years, so most household extensions stay at 20 per cent.
The table sets out the three rates as HMRC and GOV.UK describe them, checked on 10 November 2026. It is general information, not tax advice. If your project is unusual, ask the builder to show you the HMRC wording they are relying on, or take advice from an accountant.
| Rate | What the sources say | Likely for a household extension? |
|---|---|---|
| 20 per cent (standard) | Work to an existing building will normally be charged at the standard rate (Notice 708). | Yes, in most cases |
| 5 per cent (reduced) | Converting a building to increase the number of dwellings, changing residential use, or renovating a dwelling not lived in for two years. | Only in those cases |
| 0 per cent (zero) | A new house or flat, an enlargement where a new dwelling is wholly within it, and work for disabled people in their home. | Rarely |
When 0 per cent can apply
Notice 708 allows zero rating of an enlargement or extension only to the extent it contains an additional dwelling, and only where that new dwelling is wholly within the enlargement or extension. Its own example is a new eligible flat built on top of an existing building. If the new dwelling is partly inside the existing building, the zero rate does not apply under that section, although a reduced rate may be available for a conversion that changes the number of dwellings.
HMRC also names a granny annexe that cannot be used or disposed of separately from the main house as an example that does not qualify. A bigger kitchen or an extra bedroom for the same household is not a new dwelling.
When 5 per cent can apply
The empty-home rule is the one that catches homeowners' attention. Notice 708 section 8 says the 5 per cent rate can apply to renovating or altering a dwelling that has not been lived in for the two years immediately before the works start. Evidence can include electoral roll, council tax or utility records, or a letter from a council's empty property officer, and occasional use such as a second home stops the rate applying. As read on 10 November 2026, section 8.4 lists the construction of an extension among works of improvement that can be reduced-rated, and says work that needs consent which has not been granted is standard rated.
That is a narrow route, not a general one. If a builder offers 5 per cent on a house you have lived in, ask which section of Notice 708 they rely on and what evidence they hold. If they cannot say, plan on 20 per cent.
Check the guidance: HMRC: Buildings and construction (VAT Notice 708), GOV.UK: VAT rates on different goods and services, GOV.UK: VAT for builders, houses and flats.
Rugby: building control and the bills outside the builder's price
Building control in Rugby is run by Warwick Building Control, and the council page we opened does not say whether its fees include VAT, so ask before you budget.
An extension in Rugby needs more than a builder's price. Rugby Borough Council says Warwick Building Control, a partnership of Rugby Borough Council and Warwick District Council, runs building control for the borough, on (01926) 456551. Warwick District Council's page says standard fees are shown on the application forms, that larger projects need a quotation from the team and that a separate schedule of supplementary charges exists. The page does not mention VAT at all.
So do not assume that the VAT line on a builder's quotation covers every cost. Ask the builder whether the building control application is in their price or yours, and if it is yours, ask the building control team what the fee is and whether VAT is added. Do the same for an architect or designer, a structural engineer and any planning fee, because each is a separate bill and each may be quoted with or without VAT.
Check the guidance: Rugby Borough Council: Warwick Building Control, Warwick District Council: building regulations.
What three UK pages say about VAT, and where they fall short
Three pages we opened agree on 20 per cent for extensions, but each leaves something unclear, from an outdated title to a claim with no evidence.
Pages that rank for this question are mostly written by trade bodies, lead-generation sites and accountants, and the VAT sections are short. We opened three of them on 10 November 2026 and checked each against HMRC's own pages. They are market commentary, not Belmax quotations.
| Source | Date shown | What it says | What to watch |
|---|---|---|---|
| FMB | 4 March 2026 | Extensions attract 20 per cent on labour and materials; confirm if quotes include VAT | Short; no mention of reduced or zero rates |
| Whito | Headed 5 November 2026; prices checked 11 September 2026 | A VAT registered builder must add 20 per cent; 60,000 pounds plus VAT is 72,000 pounds | Says threshold builders partly explain quotes a fifth lower, with no evidence |
| Crunch | Updated 16 February 2026, under a 2025 title | Extensions at 20 per cent; empty homes may get 5 per cent with evidence | Mixed dates; energy-saving rates listed inconsistently |
Read the date before the rate
The energy-saving rate is a good example of why dates matter. GOV.UK's rates page, updated on 10 July 2026, lists materials such as insulation, solar panels and heat pumps at 0 per cent until 31 March 2027, and lists the installation of a boiler or radiators at 5 per cent. The Crunch page shows one list at 5 per cent and a later note about a temporary zero rate, so a reader could take away the wrong figure. If your extension includes any such item, ask the builder to state which rate they have applied to it and to show the date of the rule they rely on.
Check the guidance: FMB: single storey extension costs, a practical guide for homeowners, Whito: extension cost guide, Crunch: VAT on building work, zero, reduced and standard rates, GOV.UK: VAT rates on different goods and services.
A builder's VAT status changes the quotation
GOV.UK says a business must register for VAT once its taxable turnover passes £90,000, so a smaller builder may quote without VAT and a larger one will add it.
The registration page says you must register if your total taxable turnover for the last 12 months goes over £90,000, or if you expect it to within the next 30 days. The page shows no update date, so check the figure on GOV.UK when you read this. The practical effect is that two honest quotations for the same extension can differ by the VAT line alone, depending on whether each builder is registered. Whito suggests that threshold builders partly explain quotes a fifth lower, but it gives no evidence, so treat that as a possibility to ask about rather than a rule.
Do not decide on price alone. A lower total that omits VAT because the builder is not registered is a legitimate quotation. A lower total that omits VAT because the builder left it off, then adds it later, is a problem. Ask in writing whether the builder is VAT registered and whether the price includes VAT.
Check a VAT number on GOV.UK
If a builder gives a VAT number, GOV.UK's check service tells you whether it is valid and the name and address it is registered to. You need the number, as you cannot search by business name, and you will usually find it on invoices, receipts or the website. Make sure the name matches the business named on the quotation. If a builder who says they are not registered adds VAT to an invoice, ask them to explain before you pay, and keep the reply.
Check the guidance: GOV.UK: register for VAT, GOV.UK: check a UK VAT number, Whito: extension cost guide.
Materials, supplied goods and what you buy yourself
Notice 708 says the rate a builder charges for the work normally sets the rate for the building materials they fit, but goods that are not building materials stay at 20 per cent.
On a standard-rated extension this rarely changes the total, because both labour and materials are at 20 per cent. It matters on any reduced-rated project or on items that sit outside the building work. Notice 708 says that where a builder's work is reduced rated or zero rated, so are the building materials they supply and fit. It also says goods that are not building materials are standard rated, and that retailers and builders' merchants selling from stock must generally standard-rate most goods.
That last point helps if you plan to buy a kitchen, bathroom suite or tiles yourself. Ask the builder in writing who buys what, who pays the VAT on it and whether the quotation excludes any items you have chosen to supply. A provisional sum for something you have not chosen is fair, but ask whether it includes VAT, as an allowance with no VAT statement can add a fifth when the real invoice arrives.
Check the guidance: HMRC: Buildings and construction (VAT Notice 708).
Compare quotations on VAT before you compare prices
Ask every builder in Rugby to put the VAT status, the rate and the VAT amount on the quotation, so that you compare like with like.
Before you ask for prices, write down what you want each quotation to show. A one-page checklist is enough, and sending the same list to every builder makes the answers comparable.
Ask whether the total includes VAT, and show the VAT as a separate line. Ask for the rate used, and the reason if it is not 20 per cent, including the Notice 708 section the builder relies on. Ask whether the builder is VAT registered, and for the VAT number. Ask which items are excluded, such as building control fees, professional fees, kitchen or bathroom fittings and the VAT on anything you supply. Ask what happens to the VAT if the scope changes during the build, and ask for a written variation each time.
Then add the figures yourself on one page. When two totals differ by about a fifth, check VAT first, because that is the simplest explanation and the cheapest to settle. If a Rugby builder cannot answer these questions clearly before you sign, that tells you something about how the job will be managed.
What clients say
Recent words from Belmax clients.
Three public five-star review excerpts, checked 24 September 2026.
“We have been really happy with the service from Belmax Builders. They are reliable, professional and, most importantly, always kept to the agreed schedule.”
“Belmax did the job to very high standard, communicated with us the whole time and explained really well what to expect.”
“Job was started on time and Rob kept us up to date every step of the way. The finished conversion looks amazing.”
Frequently asked questions
Do you pay VAT on building an extension in Rugby?
Usually yes, in Rugby as elsewhere in England. GOV.UK says most work on houses by builders is charged at the standard rate of 20 per cent, and HMRC's Notice 708 says work to an existing building will normally be standard rated. That includes the builder's labour and the materials they fit. A builder who is not VAT registered cannot add VAT, so ask each builder in writing whether VAT is included and whether they are registered.
Can I get the VAT back on a house extension?
For a household extension charged at 20 per cent, the pages we opened offer no general way to reclaim it. GOV.UK's builders page points to separate refund guidance for people building their own home, which is a different project from extending a house. Do not budget on a refund. If you think you may qualify for something, ask HMRC or an accountant before signing, and keep your invoices.
Is an extension ever zero-rated or charged at 5 per cent?
Sometimes, but rarely for a household extension. Notice 708 allows zero rating only where a new dwelling sits wholly within the extension, and a 5 per cent rate can apply to a home not lived in for two years before the work or to certain conversions. If a builder quotes either, ask which section of Notice 708 they rely on and what evidence they hold. Otherwise plan on 20 per cent.
Should a quotation show VAT separately?
Yes, ask for it. The FMB advises homeowners to always confirm whether quotes are inclusive or exclusive of VAT. A quotation that states the total, the VAT rate and the VAT amount as separate lines lets you compare builders properly and spot an omission. If a builder is registered, they should be able to give you their VAT number, and you can check it on GOV.UK.
How do I check a builder's VAT number?
Use GOV.UK's check a UK VAT number service. It tells you whether the number is valid and shows the name and address of the business it is registered to, and you need the number because you cannot search by business name. Check that the name matches the business on your quotation. The service cannot check an application that is still waiting to hear back from HMRC.
Sources
Figures, fees and rules change. Every source below was checked on 10 November 2026.
- GOV.UK: VAT for builders, houses and flatsChecked 10 November 2026: most work on houses and flats is charged at 20 per cent; 0 per cent for a new house or flat and work for disabled people; 5 per cent for some conversions and renovating an empty home. Extensions are not named; it points to VAT Notice 708.
- HMRC: Buildings and construction (VAT Notice 708)Published 13 August 2014, last updated 26 August 2026: work to an existing building normally standard rated; zero rating for an enlargement only where a new dwelling is wholly within it; empty-home 5 per cent rate needs two years not lived in.
- GOV.UK: VAT rates on different goods and servicesLast updated 10 July 2026: lists 5 per cent for converting to increase the number of dwellings and for renovating a dwelling empty for at least 2 years; energy-saving materials at 0 per cent until 31 March 2027.
- GOV.UK: register for VATRegistration threshold of 90,000 pounds of taxable turnover over 12 months or expected within 30 days; no update date shown on the page.
- GOV.UK: check a UK VAT numberShows whether a UK VAT number is valid and the name and address it is registered to; you need the number, as you cannot search by business name.
- FMB: single storey extension costs, a practical guide for homeownersDated 4 March 2026: home extensions attract 20 per cent VAT on labour and materials; always confirm whether quotes include VAT.
- Whito: extension cost guideHeaded 'Last Updated on November 5, 2026' with prices checked 11 September 2026: a VAT registered builder must add 20 per cent; a 60,000 pound quote plus VAT is 72,000 pounds.
- Crunch: VAT on building work, zero, reduced and standard ratesShows 'Updated on: February 16, 2026' under a 'Complete 2025 guide' title: extensions standard rated at 20 per cent; empty homes may qualify for 5 per cent with evidence.
- Rugby Borough Council: Warwick Building ControlBuilding control in Rugby is run by Warwick Building Control, a partnership of Rugby Borough Council and Warwick District Council; telephone (01926) 456551.
- Warwick District Council: building regulationsStandard fees are on the application forms and large projects need a quote; the page does not mention VAT.