The VAT margin scheme for used cars, explained properly

How margin scheme VAT actually works on a used car, why it is one sixth of your profit rather than one sixth of the sale price, and the three places dealers routinely get it wrong.

Updated 1 August 2026 · 6 min read · Written for UK independent dealers

Most used cars sold by an independent dealer in the UK go out under the VAT margin scheme. It is the single most important number in the trade and also the one most often worked out on the back of an envelope, usually wrongly, usually in the dealer's disfavour.

This guide covers what the scheme is, the arithmetic, the traps, and how to price backwards from a profit target so the VAT is handled before you buy rather than discovered afterwards.

What the margin scheme is

Normally VAT is charged on the full selling price of a thing. If that applied to used cars, a dealer selling a £10,000 car would owe roughly £1,667 to HMRC, which is most of the profit on an ordinary retail unit and would make the trade impossible.

The margin scheme exists because most used cars have already had VAT paid on them once, when they were new. Charging the full rate again on every resale would tax the same car repeatedly. So instead, VAT is charged only on the margin — the difference between what you paid and what you sold it for.

The scheme is optional per vehicle, but for a normal retail unit bought from a private seller, a part exchange, or an auction lot sold on a margin basis, it is almost always the right answer.

The arithmetic

The rule is simple and worth committing to memory:

VAT due = (selling price − purchase price) ÷ 6

That is one sixth of the gross margin. Not one sixth of the sale price. Not 20% of the margin.

The reason it is a sixth rather than a fifth is that the margin you have is VAT-inclusive. If your margin is £1,200, that £1,200 already contains the VAT. To extract 20% VAT from a VAT-inclusive figure you divide by six, not multiply by 0.2.

Two things follow immediately.

A sixth of every pound of margin belongs to HMRC. When you talk about "making two grand on a car", you are describing a gross figure that is really £1,667 before you have paid for a single advert, valet or warranty.

A price drop costs you less than it looks. This is the part that surprises people, and it is worth understanding properly.

Why a £600 price cut does not cost you £600

Suppose you bought a car for £9,000 and advertised it at £11,000. Gross margin £2,000, VAT £333, retained £1,667.

The car sits. You drop the price by £600 to £10,400.

The instinct is that you have just given away £600. You have not. Your new margin is £1,400, VAT on it is £233, and you retain £1,167. Compared to the £1,667 you would have retained at full price, the drop has cost you £500, not £600.

The reason is that the VAT bill fell with the margin. Every pound you come down costs you five sixths of a pound in real terms, because the sixth was never yours.

A £600 drop on a margin car costs £500 of retained profit. A £1,200 drop costs £1,000. The relief is exactly one sixth, every time.

This matters enormously when you are deciding whether to hold out for another fortnight. If a car is costing you money to keep — and it is, in floorplan, insurance, forecourt space and the deals you cannot do because your cash is tied up — then the true cost of moving it is smaller than the sticker difference suggests.

It also means that a dealer who refuses to move price because "I'd be giving away six hundred quid" is negotiating against a figure that does not exist.

Where the scheme does not apply

Three situations break the scheme, and each one changes the maths completely.

VAT-qualifying cars. Some vehicles are sold VAT-qualifying, meaning VAT was reclaimed by a previous owner — typically ex-fleet, ex-lease, and most commercial vehicles. On these, VAT is due on the full selling price, not the margin. You can reclaim the VAT on the purchase, so it can still work, but the cash flow and the arithmetic are entirely different. Treating a VAT-qualifying car as a margin car is how a dealer discovers a £2,000 hole at the quarter end.

Commercial vehicles. Vans, pickups and most crew cabs are standard-rated. Same problem, same size of hole.

Cars you have significantly altered. Rare in normal retail, but worth knowing.

At auction, the catalogue will say which basis a lot is being sold on. It is one of the first things to check and one of the easiest to skim past when you are working through two hundred lots before a sale.

Working backwards: pricing from a profit target

Most dealers price forwards — buy the car, add a margin, see what happens. The better discipline is to work backwards from what the car will actually sell for, because the retail price is set by the market and not by your ambitions.

Suppose the market says this car retails at £11,500 and you want to retain £1,500 after VAT, with £400 of prep and a £350 warranty reserve.

Start with what you need the gross margin to be. To retain £1,500 after a sixth goes to VAT, you need a gross margin of £1,500 × 6/5 = £1,800.

Then subtract everything else from the retail price:

• Retail: £11,500
• Less gross margin needed: £1,800
• Less prep: £400
• Less warranty reserve: £350
• Maximum you can pay: £8,950

That £8,950 is your ceiling, and it is a hard number. If the car makes £9,200 at auction, you walk away — not because £9,200 is unreasonable, but because at £9,200 you are working for less than you decided your time was worth.

The same algebra runs a part exchange. If a customer wants an allowance on their car and you know what it will retail for, the maximum allowance is:

Allowance = retail − 1.2 × (target profit + prep + warranty)

The 1.2 is the 6/5 factor that grosses your target back up to include the VAT. Skip it and you will overpay on every part exchange by exactly a sixth of your target profit.

The three mistakes that cost real money

Treating margin as profit. The most common. A dealer holding out for "two grand a car" who is actually retaining £1,667 has a business plan that is 17% more optimistic than reality, before costs.

Forgetting VAT relief when discounting. The mirror image. Dealers hold stock too long because they have overestimated what a price cut costs them. Cars that should have moved in week eight sit until week twenty, and by then the market has moved down anyway and the loss is real.

Missing a VAT-qualifying lot. The expensive one. A £15,000 ex-fleet car bought as if it were margin, sold at £17,500, generates a VAT bill of £2,917 rather than the £417 you had budgeted. That is a £2,500 error on a single unit — several weeks of profit gone on one line of the catalogue you did not read.

What good practice looks like

Keep the purchase price of every unit recorded accurately and separately, including fees. The margin is calculated on the price of the car, and getting sloppy about what counts makes the whole calculation unreliable.

Check the VAT basis of every auction lot before you bid, not after you win.

When you consider a price drop, work out the retained figure rather than the sticker figure. The decision is usually easier than it feels.

And price backwards. Decide what you need to retain, gross it up by 6/5, subtract prep and warranty, and let that number decide what you bid. A ceiling written down before the auction is worth more than any amount of discipline in the hall.

A note on advice

This is a general explanation of how the scheme works in practice for the motor trade, not tax advice. The rules have detail and exceptions, record-keeping requirements are specific, and your own circumstances matter. Check your position with your accountant, and keep the stock book HMRC expects.