Which mixed-use premises vat rules apply when you split a home office and commercial space and how to reclaim correctly

When you split a property into a home part and a commercial part, VAT can quickly feel like a maze. I see this a lot with small business owners who run a client-facing part of their work from a converted ground floor or have a self-contained studio next to their own living space. The rules depend on whether the supplies (rent, services, purchases) are taxable, and whether the costs are used solely for business, solely for private use, or for both. Below I set out the common situations, how I would approach reclaiming VAT correctly, and practical steps and evidence you’ll want to keep.

Which supplies attract VAT in mixed-use premises?

First, you need to identify whether the different bits of your property attract VAT at all. In simple terms:

If a part of the property is residential (private) and stays that way, rent and sales connected to that residential part are generally VAT exempt.

Commercial premises (shops, offices, workshops) are normally standard-rated, unless the landlord has opted to tax or a special VAT relief applies.

New builds or certain conversions may be zero-rated for the sale of the building (to the first purchaser) but that’s a specific situation.

So if you have a shop or office space that’s clearly commercial, purchases and VAT on rent there are likely reclaimable by a VAT-registered business. If a room is genuine residential accommodation (your bedroom, living room), costs relating to that are private and not recoverable.

Who can reclaim VAT?

You can only reclaim VAT if you’re VAT-registered and the goods or services are used for the purpose of making taxable supplies. If you operate as a sole trader, partnership or limited company and you use part of the building exclusively for business, you can reclaim VAT on purchases and ongoing costs that relate only to that business area.

For costs that benefit both business and private use, you must make a reasonable and supportable apportionment and only reclaim the business proportion.

Common areas of confusion and how I decide the split

Here are typical cost categories and how I approach them:

Utilities (electricity, gas, water) — If separate meters exist, reclaim VAT on the meter serving the business. If a single meter serves both, apportion by floor area, number of rooms used for business, or a usage diary (e.g. time spent working at home). I prefer meter or floor-area apportionment backed by a short diary for the first year to show reasonableness.

Rent — If you rent a self-contained commercial unit, VAT can be reclaimed if the supply is standard-rated. If you rent a whole residential property and use part as a home office, rent is generally exempt and VAT cannot be reclaimed.

Repairs and maintenance — If work is done only to the commercial area, reclaim full VAT. For shared repairs, apportion by floor area or by estimated share of use. Keep detailed invoices showing which rooms were worked on.

Capital costs (furniture, equipment, doors/windows) — If an item is used only in the business area, reclaim fully. If dual-use, apportion. For high-value items, the Capital Goods Scheme (CGS) may mean you must adjust your input VAT over several years if business/private use changes (see below).

Shared services (internet, phone) — Apportion based on business usage (calls, data). Many small businesses use a simple percentage — again, back this up with records.

Apportionment methods I use and recommend

HMRC expects a fair and justifiable method — there’s no single mandatory formula. Common, acceptable approaches:

Floor area — Business area (m2) ÷ total usable area (m2). This is simple and widely accepted for property-related costs.

Time-based — If the room is used for work a certain number of hours per week, apportion by hours (works well for a dedicated home office used part-time).

Meter/usage — Where separate meters exist, use actual consumption figures.

Whichever method you choose, document why it’s reasonable and keep supporting evidence (plans, meter readings, diaries). I favour floor area for fixed costs and time/usage for utilities and telephony.

Capital Goods Scheme (CGS) — when you must watch your reclaim

If you buy or improve an asset for more than the CGS threshold (currently around £2,000), you reclaim input VAT initially based on expected business use, but you must monitor use and adjust the reclaim proportionally over a spreading period (normally 5 years for buildings, shorter for other assets). If business use falls, part of the VAT must be repaid. If business use increases, you may be due additional reclaim.

This is particularly relevant where a room could be switched from commercial to residential or vice-versa (for example, converting a commercial unit back into living space). I always flag CGS to clients buying expensive fixtures or altering the structure.

Record-keeping and evidence

Good records are the backbone of a correct VAT reclaim. Keep:

Invoices and receipts referencing the supplier VAT number;

Floor plans showing business vs private areas (annotated if needed);

Meter readings and bills;

A short policy note explaining your apportionment method and why it’s reasonable;

Diaries or rotas for shared use items in early years to support time-based split.

If HMRC queries your reclaim they will expect a tidy audit trail — I’ve seen claims rejected simply because the apportionment was undocumented.

Practical examples

Situation	Apportionment method	VAT reclaim outcome
Self-contained shop at front, family home at rear	Separate meters & separate access	VAT on shop utilities and repairs reclaimable in full; no reclaim for private home
Whole house, one room as office	Floor area or time-based (hours used)	Proportionate VAT reclaim on utilities, cleaning, repairs for business share only
Shared building where landlord “opts to tax”	Floor area allocation, supported by lease	Reclaim VAT on your share of rent and service charges if part is commercial and you are VAT-registered

Practical checklist before you reclaim

Are you VAT-registered and making taxable supplies?

Is the supply you’re reclaiming VAT on (rent, work, goods) VATable or exempt?

Is the cost solely business, solely private, or mixed?

Have you chosen and documented a reasonable apportionment method?

Do you have invoices, plans, meter readings or diaries to support your claim?

Have you considered Capital Goods Scheme implications for high-value purchases?

If you’d like, send me the basic layout of your premises (a simple sketch is fine) and a list of the costs you want to reclaim. I can suggest a defensible apportionment method and a short template note you can keep with your records — that’s often enough to make HMRC queries much less stressful.