Garage conversion invoice template UK (2026): CIS, VAT and stages

A garage conversion invoice has to explain what was surveyed, stripped, steeled, insulated, boarded, wired and finished - not a vague "garage done" line. "Supply and convert garage as agreed" does not tell a householder whether an integral single garage became a living room, office, bedroom or wet-room gym, whether the up-and-over door was removed and infilled, or whether electrics and plumbing were free-issue. It does not tell a contractor's QS which plot or PO to release, or how much is labour versus the direct cost of steels, insulation, plasterboard, new frontage windows and first-fix materials you paid for.

Garage conversions are not loft packages and not full house extensions - use the loft conversion and extension templates for those. This page covers converting an existing integral or detached garage into habitable or ancillary living space (office, playroom, bedroom, gym, utility, wet room), including door removal, infill, new frontage, insulation, plasterboard, services and finishes. A garage-plus-side-extension hybrid should name both scopes clearly, or use the extension guide for the new-build wing.

Who pays matters. Billing a private householder on their own home: normal invoice, no CIS. Billing a main contractor for construction operations: often CIS. HMRC's CISR14100 treats alteration, repair or extension of buildings as construction operations (FA04/S74(2)(a)). Converting a garage on an existing dwelling is typically alteration of a building when a CIS contractor pays you. When works sit in a wider preparatory or finishing package, CISR14240 is also relevant. Soften if you only manufacture or deliver materials with no install - CISR14220 and FA04/S74(3)(c) keep manufacture/delivery of building components alone outside CIS. Supply-plus-install can pull the whole payment into CIS (CISR14020 / CISR14030). Private householders are not CIS contractors - see the public CIS overview.

VAT is separate. If VAT-registered, an ordinary garage conversion on an occupied existing home is usually 20%. Do not claim VAT-free or 0% for a normal garage-to-room conversion. VAT Notice 708 reduced rates (often 5%) only when conditions are met - for example a change in the number of dwellings, a qualifying empty-home renovation, or non-residential to dwelling conversion. Soften absolute claims; check Notice 708 and your VAT adviser. Design fees are usually standard-rated. Never reverse-charge a private householder.

This guide gives copy-paste fields, labour/materials splits, deposits, stages, four worked examples and CIS/VAT/DRC treatment. Figures are illustrative only, not market rates. InvoiceAdept does not decide CIS or VAT status and does not file CIS300, VAT returns, MTD updates or Self Assessment. It does not issue Building Control certificates, planning permissions or Party Wall awards.

Related: builder, loft, extension, electrician, plumber, deposit, reverse charge, how to invoice a UK tradesperson client.

Checked 6 September 2026. General information only - not tax, legal, Building Regulations, Party Wall or planning advice. InvoiceAdept is from Tech Me Today Ltd, Companies House 15917255, ICO ZB944663.

In short

Start by identifying who pays you, what garage type you converted (integral, detached, double, garage-plus-extension), whether the door was removed and infilled, and whether the contract is supply-only or supply-and-install.

Private householder, own-home garage conversion: no CIS. The householder is not a CIS contractor. If VAT-registered, an ordinary garage conversion at an existing lived-in home is usually 20%. Show survey, strip, steels/structure, garage door removal and infill, new frontage, insulation, plasterboard, first/second fix, electrics, plumbing (if wet room), waste and snag clearly. Do not claim "VAT free" because it is a garage conversion.

Garage conversion package for a CIS contractor: typically within CIS when a contractor pays for alteration of a building (CISR14100; FA04/S74(2)(a)). Cite CISR14240 for finishing/prep packages. Split labour from materials at direct cost (CISR15060 / CISR15090).

Manufacture and delivery of materials only (no install): generally outside CIS (CISR14220; FA04/S74(3)(c)). A mixed contract that supplies steels, windows or kits and includes installation can pull the whole contract into CIS (CISR14020 / CISR14030).

VAT reduced rate (5%) or zero: only when Notice 708 conditions are actually met. Ordinary garage conversions on an occupied house stay 20%. Never reverse-charge a householder. Never invent 0% for a normal garage-to-room job.

Take a numbered deposit before ordering steels, insulation, windows, doors or wet-room kits if your terms require one. Use stages: survey/deposit, strip and structure, weathertight/infill, insulation/first fix, finishes/snag. Keep window upgrades, wet-room adds or frontage changes as variations.

Use the invoice generator. Free: five invoices/month. Pro £7.99 excl VAT (WhatsApp). Pro+ £12.99 excl VAT (CIS). Stripe's fees apply (UK cards 1.5%+20p); InvoiceAdept adds no platform fee.

Who this garage conversion invoice template is for

For UK garage-conversion specialists, builders delivering garage-to-room packages, and subcontractors who strip, steel, infill, insulate, board, wire or finish converted garages. Paperwork pattern only - not a price list, Building Control or planning document.

• Garage conversion specialists (integral, detached, double, annex-style day room)

• Builders who include garage conversions in residential packages

• Structural / steel installers billing garage beams, padstones and floor build-ups

• Bricklayers / carpenters infilling garage door openings and forming new frontages

• Insulation, plasterboard and drylining crews on garage conversions

• Electricians billing lighting, sockets, data and consumer-unit works as part of a package (or separately)

• Plumbers billing wet-room or utility plumbing in a converted garage

• Subcontractors to main contractors on residential garage-conversion packages

• Sole traders and limited companies who need CIS and VAT lines that match the payer

If your day job is a full rear extension, loft conversion or stand-alone electrics/plumbing with no garage focus, use the extension, loft, electrician or plumber guides and come back here for garage-specific lines.

Three garage conversion jobs, three invoices

These three jobs can use similar steels and insulation but need different invoice logic.

A main contractor can be the CIS contractor even when the finished room serves a tenant or homeowner. If the builder engages you, your invoice is to that builder. That contractor-to-subcontractor payment is the one to test. If the householder hires and pays you directly, the householder invoice has no CIS.

What garage conversion work belongs on the invoice

Do not compress a multi-week garage conversion into "supply and convert garage". Describe survey, strip, structure, door removal and infill, new frontage, insulation, services and finishes, and what another firm supplied.

Conversion types to name clearly on the face of the invoice

What a UK garage conversion invoice must include

UK invoices need the basics HMRC and customers expect. See GOV.UK invoicing guidance. For VAT-registered traders, VAT invoices need the extra fields in that guidance and your VAT registration number.

VAT registration threshold is £90,000 (see VAT registration). Do not use outdated £85,000 figures. Deemed contractor status for CIS turns on construction spend of more than £3 million in the relevant period - never quote £1 million as the current threshold.

Copy-paste garage conversion invoice fields

Use this as a checklist when building the invoice in software or on paper.

Invoice number: GC-2026-00XX
Invoice date:
Tax point (if different):

From:
[Trading name]
[Address]
[Phone / email]
[VAT number if registered]
[Company number if limited]

Bill to:
[Householder OR contractor company name]
[Site address / plot / PO]

Job reference / quote number:
Property / garage type: [integral single | integral double | detached | garage+extension | repair/reboard | supply-only]
End use: [living room | office | bedroom | gym | utility | wet room | other]
Garage door: [removed and disposed | retained | by others]
Infill / new frontage: [brick/block/stud infill | window | French doors | render - as drawing ...]
Steels / structure: [yes - sections ... | by others | none required]
Insulation / plasterboard: [spec ...]
Drawing / Building Control ref (if any):

Line items:
1. Survey / design / access / scaffold - £...
2. Strip-out / preparation - £...
3. Steels / structural / floor build-up - materials at direct cost £... ; labour £...
4. Garage door removal and disposal - £...
5. Opening infill - materials £... ; labour £...
6. New frontage window / doors - materials £... ; fit labour £...
7. Insulation - materials £... ; labour £...
8. Plasterboard / linings - £...
9. Electrical first/second fix - £...
10. Plumbing / wet room (if included) - £...
11. Floor finishes (if included) - £...
12. Variation [ref] - £...
Less: Deposit credit INV-... - (£...)
Less: CIS deduction (if applicable) - (£...)
VAT (or reverse charge statement) - £...
Amount due - £...

Payment: bank details / Stripe
Due date:
CIS: UTR ... Verification ... Rate 20% / 30% / 0% gross (contractor jobs only)
Building Control: fee charged separately / by client - ref ...
Planning / permitted development: client responsibility / noted separately - invoice is not consent

Sole trader versus limited company

InvoiceAdept supports both patterns. It does not file your CIS300 or VAT return either way.

Labour versus materials for garage conversion CIS

For CIS, materials at direct cost can be excluded from the deduction base (CISR15060 / CISR15090). Mark-up is not materials. Free-issue steels, windows or boards from the contractor are not your materials - note them as free-issue so you do not claim them in the materials exclusion.

CIS deep dive: garage conversions as building alteration

Garage conversion work paid by a CIS contractor is usually construction operations because it alters an existing building. Prefer CISR14100 for alteration, repair or extension of buildings (FA04/S74(2)(a)). Use CISR14240 when the package is preparatory or finishing work bringing construction to completion (scaffold, insulation as part of a wider project, certain fittings). Materials-only supply without install sits under CISR14220. Mixed contracts: CISR14020 / CISR14030. Materials at direct cost only: CISR15060 / CISR15090.

Householder invoices never carry CIS deduction blocks. Contractor invoices need UTR, verification outcome and a clear labour/materials split when deduction applies.

VAT: the "VAT free garage conversion" myth versus Notice 708

An ordinary garage conversion on an occupied existing dwelling is usually standard-rated at 20% if you are VAT-registered. Calling the finished space an "office", "gym", "annexe" or "extra bedroom" does not make it VAT-free.

Soften every absolute claim. Check VAT Notice 708 and take advice before issuing a 5% invoice. Never invent 0% for a normal occupied-home garage conversion. Never reverse-charge a genuine zero-rated ESM (exempt or outside-scope) supply - and never reverse-charge a private householder.

Domestic reverse charge

Domestic reverse charge may apply when all of these hold: both parties VAT-registered; the supply is construction services reported within CIS; the rate would otherwise be standard or reduced (not zero); and the customer is not an end user. Never reverse-charge a private householder. See InvoiceAdept's domestic reverse charge invoice guide.

Scaffold, electrics, plumbing and specialist trades on the invoice

Garage conversions often pull in several trades. Keep the face of the invoice clear about who did what.

Deposits and staged payments for garage conversion packages

Multi-week garage conversions need staged cashflow. Take a numbered deposit before ordering steels, insulation, windows or wet-room kits if your terms require one. Then invoice recognisable milestones.

Figures for deposit percentages are commercial choices - mark them illustrative only when you show examples. Do not invent "industry standard" percentages. See the deposit invoice template.

Variations and retention

Extra windows, French doors instead of a casement, wet-room adds, underfloor heating, flooring upgrades or frontage render changes should be written variations referencing the original quote - not silent final-total increases.

If retention is held on a contractor package, show withheld and released amounts on separate lines. For householders, keep consumer-friendly stage language - do not paste commercial retention onto a domestic job unless the written contract uses it.

Worked examples A-D

All money figures below are illustrative only. They are not market rates, quotes or a price list.

Example A - domestic integral garage conversion for a householder (20% VAT, no CIS)

Private householder; integral single garage to living room / home office; door removed and infilled; new frontage window; no CIS.

No CIS block. Deposit of £2,500 (illustrative) would appear as a separate numbered invoice then as a credit on stage or final invoices.

Example B - contractor garage conversion package (CIS 20%, reverse charge)

VAT-registered subcontractor to VAT-registered main contractor; integral garage conversion as finishing package; CIS verified 20%; reverse charge applies (illustrative assumption that tests are met).

Show UTR, verification and reverse-charge wording clearly. Materials at what you paid (CISR15060 / CISR15090). Free-issue window from the contractor: note separately; do not invent a cost.

Example C - empty-home renovation garage conversion (CIS; VAT depends)

Garage works inside a wider empty-home renovation. CIS usually applies when a contractor pays you. VAT may be 5% only if Notice 708 empty-home / qualifying conversion conditions are actually met - soften and take advice; do not assume 5% from "empty" alone.

Document emptiness period, change-of-dwellings facts or other Notice 708 evidence before putting 5% on the face. Soften absolute claims. If reverse charge also applies, the customer accounts for VAT at the applicable rate - never invent 0% ESM reverse charge.

Example D - materials-only steel and window delivery, no install

Supply of steels and frontage window delivered to site; no fitting. Generally outside CIS (CISR14220; FA04/S74(3)(c)). Usually standard-rated VAT if you are registered.

If a later variation adds installation labour under the same contract, revisit mixed-contract CIS rules (CISR14020 / CISR14030) - supply-plus-install can pull the whole contract into CIS.

Building Control, Party Wall and planning - the invoice is not a certificate

An invoice is a request for payment and a commercial record. It is not:

• a Building Control completion or final certificate

• planning permission or lawful development / permitted development confirmation

• a Party Wall Act award

• an electrical Part P / competent person notification

• a plumbing / gas / WRAS certificate (unless that professional issues their own document)

• structural engineer sign-off (unless that professional issues their own document)

Garage conversions often need Building Regulations approval (structure, insulation, fire, ventilation, electrics). Planning or permitted development questions depend on use, frontage changes and local rules - that is the client's position, not something your invoice proves. High-level only: check GOV.UK and the local planning authority / Building Control body. If you collect a Building Control fee, show it as a disbursement with the receipt reference. Party Wall awards stay separate. InvoiceAdept does not issue Building Control certificates, planning permissions or Party Wall awards.

Late payment (brief)

The Late Payment of Commercial Debts (Interest) Act 1998 is a B2B regime, not automatic against private householders. For qualifying commercial debts, statutory interest is Bank Rate + 8pp (SI 2002/1675). Bank Rate was 3.75% on 30 July 2026 → statutory 11.75% while that rate applies - check the live Bank of England rate. Next decision referenced: 17 September 2026. Compensation bands £40 / £70 / £100. Do not paste commercial late-payment wording onto consumer invoices.

Making Tax Digital means records, not filing

InvoiceAdept creates and stores invoice records. It does not file VAT returns, CIS300, MTD updates or Self Assessment, and does not decide VAT rates or submit Building Control/planning paperwork. MTD for ITSA phases in by turnover: over £50,000 from 6 April 2026; £30,000 from April 2027; £20,000 from April 2028. Keep digital records; filing remains your (or your accountant's) job.

How InvoiceAdept helps garage conversion contractors

InvoiceAdept turns quotes and stage history into readable invoices - not HMRC software or a Building Control platform.

Separate survey, strip, steels, door removal/infill, frontage, insulation, electrics, plumbing, deposits and variations; send PDF; offer Stripe where enabled. No InvoiceAdept platform fee on Stripe (Stripe's own fees apply - UK cards 1.5%+20p). See pricing, CIS features and the invoice generator.

Quote versus invoice versus retention on contractor packages

A quote is an offer. An invoice is a request for payment against agreed or certified work. Retention is a contract term, not a tax rule.

Mistakes that bounce garage conversion invoices

FAQ

Does a garage conversion come under CIS?

Often yes when a CIS contractor pays you for construction operations that alter a building - for example converting an integral or detached garage into a room. Prefer CISR14100 (alteration, repair or extension of buildings; FA04/S74(2)(a)). Use CISR14240 when works are part of a preparatory or finishing package. A private householder paying you directly is not a CIS contractor.

Does a householder deduct CIS from a garage conversion contractor?

No. A private householder is not a CIS contractor. Domestic garage-conversion invoices should not carry CIS deduction blocks. See the public CIS overview.

Are integral and detached garage conversions within CIS for contractor jobs?

Typically yes when a contractor pays for alteration of a building (CISR14100), or as finishing/prep within a wider package (CISR14240). Split labour and materials; show UTR and verification as your process requires. Detached garages are still buildings for this purpose when you alter them under a construction contract - facts matter; take advice on edge cases.

What if I only supply steels, windows or insulation kits with no installation?

Manufacture and delivery of building components without installation is generally outside CIS (CISR14220; FA04/S74(3)(c)). Mixed contracts that also include install need careful reading of the mixed-contract rules (CISR14020 / CISR14030) - supply-plus-install can pull the whole contract into CIS.

What can I treat as materials for CIS on a garage conversion job?

The direct cost of materials you paid for on that contract - steels, blocks, timber, insulation, plasterboard, windows, doors, DPM, cable, pipework, sanitaryware, fixings - supported by evidence (CISR15060 / CISR15090). Mark-up is not direct-cost material. Free-issue materials from the contractor are not your materials.

Is a garage conversion VAT free in the UK?

Usually no. An ordinary garage conversion on an occupied existing home is typically standard-rated at 20% if you are VAT-registered. Do not claim VAT-free or 0% for a normal garage-to-room job. Soften absolute claims; check VAT Notice 708 and your adviser.

When can garage conversion works be 5% VAT?

Possibly when Notice 708 conditions for a qualifying residential conversion (change in number of dwellings), empty-home renovation (typically empty 2+ years), or non-residential to dwelling conversion are met. Soften absolute claims; document the facts and take VAT advice. Calling a room an "office", "gym" or "annexe" does not create a 5% claim on an occupied house.

When does reverse charge apply to garage conversion invoices?

When the domestic reverse charge tests are met: both parties VAT-registered, the supply is construction services reported within CIS, standard or reduced (not zero), and the customer is not an end user. Never reverse-charge a householder. Never invent reverse charge on genuine 0% ESM supplies. See the DRC invoice guide.

Should I invoice a deposit before ordering steels, windows or insulation?

If your terms require a deposit, yes - raise a numbered deposit invoice, then credit it on stage or final invoices. See the deposit invoice template.

How should I invoice an extra window, French doors or wet-room add?

As a written variation referencing the original quote, not as a silent increase on the final total.

How should garage door removal and opening infill appear on my invoice?

As separate clear lines (or a named package line that still describes both): door removal/disposal, then brick/block/stud infill and new frontage. Vague "frontage works" lines bounce when the QS or householder cannot match the opening.

Does InvoiceAdept file CIS, VAT or MTD returns, or issue Building Control / Party Wall certificates?

No. It creates and stores invoices. CIS features are on Pro+ at £12.99 excl VAT; Pro is £7.99 excl VAT with WhatsApp send; Free is five invoices per month. It does not file CIS300, VAT returns, MTD updates or Self Assessment and does not decide tax status. It does not issue Building Control certificates, planning permissions or Party Wall awards.

What CIS rates should appear if the contractor deducts?

20% verified, 30% unverified, or 0% with gross payment status - whatever verification outcome applies. InvoiceAdept does not verify you with HMRC.

Is the VAT registration threshold still £90,000?

Yes - £90,000. Do not use £85,000. Deemed contractor construction spend is more than £3 million, not £1 million.

Does MTD for Income Tax mean InvoiceAdept files my Self Assessment?

No. MTD ITSA phases in by turnover (over £50,000 from 6 April 2026; £30,000 from April 2027; £20,000 from April 2028). InvoiceAdept helps you keep invoice records; it does not file MTD updates or Self Assessment.

Related guides

• Builder invoice template UK

• Loft conversion invoice template UK

• Extension invoice template UK

• Electrician invoice template UK

• Plumber invoice template UK

• Deposit invoice template UK

• Domestic reverse charge invoice UK

• How to invoice a client UK tradesperson

Pricing · CIS invoices · Invoice generator

About this guide

Written for UK garage-conversion specialists, builders and subcontractors who need householder and contractor invoices that survive QS review and CIS/VAT scrutiny. Last reviewed 6 September 2026. Canonical URL: https://invoiceadept.com/blog/invoicing/garage-conversion-invoice-template-uk/.

General information only - not tax, legal, Building Regulations, Party Wall or planning advice. InvoiceAdept is a product of Tech Me Today Ltd, Companies House 15917255, ICO ZB944663.

Bottom line

Name the garage type, door removal/infill and new frontage. Split labour and materials for CIS - and remember CISR14100 puts alteration of buildings in scope when a contractor pays. Keep householder invoices free of CIS. Treat VAT carefully - ordinary occupied-home garage conversions are usually 20%, not VAT-free; Notice 708 5% only when conditions are evidenced. Use deposits and variations for multi-stage packages. Distinguish garage conversions from lofts and full extensions. InvoiceAdept helps you issue the paperwork; it does not file HMRC returns or issue certificates.