The Complete Guide to Dealer Invoice Management: Streamline Your Workflow

Last updated 24 September 2026.

Dealer invoice management means raising the right invoice at each point in a car’s life (purchase, preparation costs, sale and any finance) with the correct VAT treatment, and keeping records HMRC can check. If the invoices are right, your VAT return, stock book and profit figures follow from them. If they are wrong, you find out at your VAT return or, worse, at an HMRC visit.

This guide covers each invoice a car sale needs, how margin scheme and standard VAT change them, and the records you have to keep.

This is general guidance based on HMRC’s published rules, not tax advice. Check anything you are unsure about with your accountant.

Why invoice management matters for dealers

Your invoices are the source for your VAT return, your stock book and your profit figures, so a mistake on one invoice shows up in all three. Each car you sell produces several documents: a purchase invoice, cost records for preparation, a sales invoice and, on finance deals, paperwork for the finance company.

Errors cause four kinds of trouble:

• Wrong VAT returns, which can lead to HMRC penalties
• Wrong profit figures, so you can’t see your real margin
• Margin scheme records that don’t meet the VAT margin scheme rules
• Time lost chasing paperwork and reconciling figures by hand

The dealer invoice workflow

A car’s invoices follow its journey through your business: purchase, costs, sale and, when there is finance, the finance company.

1. Purchase invoice

Raise a purchase invoice the day you buy a car, whether it comes from a private seller, an auction or a part exchange. When you buy a margin scheme car from a private seller or a business that is not VAT registered, HMRC expects you to make out the purchase invoice yourself, showing:

• The seller’s name and address, and yours
• The stock book number, so the invoice and the stock book can be matched
• The date
• A description of the car, with its registration number
• The total price, with no other costs added
• The words “margin scheme - second hand goods”

It also pays to record the mileage, the VIN and the car’s VAT status (margin scheme or VAT qualifying), because everything later depends on them. If you are not sure which a car is, see VAT qualifying cars explained.

In Haswent’s dealer management system, you add the car by its registration and the specification is filled in. You record what you paid, and who from, on a purchase invoice, and you can upload supplier invoices as PDFs. Every part exchange gets its own purchase invoice when the deal is completed.

2. Cost tracking

Record every preparation cost against the car it was spent on, not against the business as a whole. MOT work, servicing, valeting, bodywork and alloy refurbishment all come off the profit on that car.

When costs are only recorded at business level, you can’t work out the stand-in value of each car, and every profit figure is too high. In Haswent, you add costs to a car from your own list of regular costs, and they are added to the purchase price to give its stand-in value.

Keep in mind that these costs do not change your margin scheme VAT. HMRC does not let you add repair or preparation costs to the purchase price when you work out the margin. You reclaim the VAT on those costs in the normal way instead.

3. Sales invoice

The sales invoice records who bought the car, what they paid and how the VAT is treated. It needs:

• The buyer’s name and address
• The vehicle details, matching the stock record, including the registration number
• The selling price
• The VAT treatment: margin scheme or standard VAT
• How the customer paid: cash, finance, bank transfer or card

For a margin scheme sale, HMRC also expects your name, address and VAT registration number, an invoice number, the date and the words “margin scheme - second hand goods”.

In Haswent, completing a deal raises the sales invoice from it: the car, add-ons and fees, the part exchange and every payment taken, with the balance due worked out. See car sales invoicing for the details.

4. Finance company invoices

When a customer buys on finance, the finance company is usually the buyer, so the sales invoice is made out to them. Keeping the finance paperwork separate from your own commission keeps your records clean and your finance introductions properly documented.

In Haswent, completing a deal with finance on it makes the sales invoice out to the finance company, with your customer as the delivery address. If you have recorded your commission, a separate commission invoice to the lender is raised too.

VAT management in invoicing

UK car dealers sell under two VAT treatments, and each car must be invoiced under the right one: the margin scheme or standard VAT.

The VAT margin scheme

Most used cars sold by VAT-registered independent dealers go through the VAT margin scheme. Under the scheme:

• VAT is one-sixth of your margin, the selling price minus the purchase price
• VAT must not be shown separately on the sales invoice
• The buyer cannot reclaim any VAT

Our free VAT margin calculator works out the VAT due on a single car.

Standard VAT (qualifying vehicles)

You cannot use the margin scheme for a car you bought on an invoice that shows VAT separately, whether or not you reclaimed the VAT. Cars bought that way, often called VAT qualifying cars, are sold under the normal rules:

• VAT is charged at 20% on the full selling price
• VAT is shown separately on the invoice
• A VAT-registered buyer can reclaim it

You can also choose to sell an eligible car under the normal rules instead of the margin scheme, for example when a business buyer needs a VAT invoice.

One car invoiced under the wrong treatment is enough to put your VAT return out. In Haswent, you set each car in stock to No VAT/Margin, Inc VAT or Ex VAT once, and every invoice for that car follows it.

Common invoice errors and how to avoid them

The four mistakes dealers make most often are mixing up VAT treatments, missing cost records, incomplete buyer details and sums done by hand.

1. Mixing up VAT treatments

Putting a qualifying car through the margin scheme, or the other way round, usually happens because the car’s VAT status wasn’t recorded when it was bought.

Record the VAT status when you buy the car and let your DMS apply it to every invoice after that.

2. Missing cost records

If costs aren’t recorded against each car, your profit figures are too high and your buying decisions are based on margins you never made.

Use a system that records costs per car, and add each cost when you pay it, not at the month end.

3. Incomplete buyer details

Invoices with missing or wrong buyer details cause problems if HMRC checks your records. Every sales invoice needs at least the buyer’s full name and address.

Take buyer details from a customer record linked to your invoicing, so they are entered once and reused.

4. Mistakes in manual sums

Working out margin scheme VAT by hand across dozens of cars a month invites mistakes, and one wrong figure carries through to your VAT return.

Let your DMS do the sums. In Haswent, the VAT margin report under Insights works out the VAT due on your margin for the period.

Stock book management

If you use the margin scheme, HMRC requires you to keep a stock book: a record of every car you buy and sell under the scheme. HMRC’s list of what it must show includes the stock number, purchase date and price, purchase invoice number, seller, registration and description, and on sale the date, sales invoice number, buyer, selling price, margin and the VAT due.

Keeping a stock book by hand is slow and easy to get wrong. With a DMS, the stock book comes from the purchase and sales records you already keep. In Haswent, the stock book, stock on date and vehicle holding reports show what you bought, sold and held, what it cost and the profit made.

Profit and loss visibility

When every purchase, cost and sale is recorded properly, your profit and loss reports are accurate without extra work. You can see:

• Profit on each car
• Your profit and loss for the month
• Average margins, which help you buy better
• Stock age, so you can spot cars taking too long to sell

Haswent has profit and loss, payments and transactions reports for the dates you choose. If you keep your books in Xero, the Xero integration sends paid invoices and payments across after you preview and confirm them.

How Haswent handles invoicing

Our dealer management system raises your invoices from the same stock and deal records you already keep:

Not ready for a DMS? Our free car sales invoice generator makes a one-off invoice in your browser. For the rest of your software, see our dealership software guide.

HMRC sources

• Using the VAT margin scheme for second-hand vehicles
• Selling second-hand vehicles using a VAT margin scheme
• Record keeping for VAT (VAT Notice 700/21)

Frequently Asked Questions

Keep your invoicing in one place

If you invoice by hand or across several systems, you spend more time on admin than you need to and take more risk with your VAT. Our dealer management system keeps every invoice, from purchase to sale, with the car and the customer it belongs to.

Get in touch with our team to see how Haswent would handle your invoicing.