UK garage invoicing: VAT, labour rates, and what to include

Most UK garage invoices I see are technically wrong in at least one small way. Usually it does not matter. Occasionally it costs the workshop a chargeback, a VAT correction, or an annoyed accountant. This is a practical guide to what HMRC actually requires, what is normal in the trade, and the four mistakes I see most often.

I am not your accountant. If you have specific VAT questions, talk to one. What follows is the baseline every workshop owner should know without paying for an hour.

What a UK invoice legally must contain

HMRC's rules vary slightly depending on whether you are VAT registered. The non-negotiable baseline for every invoice, VAT registered or not:

• Your business name and address
• The customer's name and address
• An invoice number, unique and sequential (do not skip numbers, do not duplicate)
• The invoice date
• A description of goods or services supplied
• The total amount charged

If you are VAT registered (mandatory above the £90,000 12-month turnover threshold as of April 2024, the most recent uplift), you also must include:

• Your VAT registration number
• The VAT rate applied to each item (most workshop services are 20 percent standard rate)
• The net amount (before VAT) for each item
• The total VAT amount
• The total gross amount (net plus VAT)
• The date of supply if different from the invoice date

If you are below the VAT threshold and not registered, you must not charge VAT and you must not put a VAT registration number on the invoice. Putting one on by mistake is the single most common error I see, usually because the workshop owner copied an invoice template from a VAT-registered colleague.

The four invoicing mistakes I see most often

1. Charging VAT when not registered. The workshop is under the threshold, the owner uses an invoice template from a friend's garage, the template has "VAT 20%" baked in. The customer is now paying VAT that does not go to HMRC, the workshop is technically misrepresenting itself, and if the customer challenges it the workshop has to refund.

2. Skipping invoice numbers. Owner generates an invoice in Word for one customer, in a workshop tool for another. Numbers come out of sequence. HMRC takes a dim view of this during a VAT inspection. Pick one system, use one sequential numbering scheme.

3. No payment terms on the invoice. "Payable on receipt" is fine. "Net 14" or "Net 30" is fine. Nothing at all is technically valid but causes endless payment-chasing arguments. Always state the terms.

4. Adding parts markup invisibly. Workshop pays £40 for a part, charges the customer £60, lists "Part: £60" on the invoice. Legal, fine, normal. But when the customer challenges the price you have no audit trail of your own cost. Some workshops list net cost and "supply margin" separately, which is more defensible but visually noisier. Pick a style and be consistent.

Labour rate transparency

There are two broad schools.

The transparent school lists the labour rate clearly on the invoice, breaks down hours per task, multiplies through. "Front brake pads, 1.2h labour at £65/hr = £78." Customers see exactly what they paid for. Disputes are easier to resolve.

The flat-rate school lists a fixed price per job. "Front brake pads replacement: £165." The labour rate is implied but not stated. Customers see one number. Disputes are harder because the customer cannot tell whether they paid for 30 minutes or three hours.

Both are legal. Both are common. The transparent school wins on trust and is easier to defend if a customer escalates. The flat-rate school wins on selling premium work because the breakdown is hidden.

My opinion: transparent for routine work (services, MOT, brake jobs), flat-rate for diagnostic work where the time is unpredictable but the answer is what matters. Mixing them on the same invoice is fine. Just be clear which is which.

Parts markup: what is normal in UK independents

Independent workshops in the UK typically mark parts up between 15 and 30 percent above net trade price. This is not industry guidance, it is what owners tell me they actually do. Below 15 percent, you are not making a sensible margin on the working capital tied up in stock. Above 30 percent, customers start comparing to online prices and pushing back.

Quick-fit chains often run higher (30 to 50 percent) because they price as a package, not a parts plus labour line. Main dealers are higher still.

The unfair comparison customers will throw at you: "I can get this part for £35 on Eurocarparts." Sometimes true. Your defence is that you guarantee the work, you fit it, you stand behind it, and you carry the warranty risk. That is worth something. How much depends on what your local market will bear.

What is not defensible: marking up the part 60 percent and pretending it is the trade price. Customers can check. They will check. Eurocarparts is one click away.

Payment terms that actually work

"Payment on collection" is the default for most independent workshops, and it should be. You are not a credit business. The job is done, the car is fixed, the customer pays before the keys leave the desk.

For trade customers (body shops, fleets, dealers) you will often need 14 or 30 day terms. Two safeguards make this work:

• Get the agreed terms in writing before the first job. Email is fine.
• Stop work for any customer who is more than 7 days past terms on a previous invoice. Do not extend more credit until they clear.

The customers who pay late once will pay late again. The customers who pay on time the first time will keep paying on time. This is not a moral judgement, it is just operational reality. Trust your data, not their excuses.

Net 14 vs Net 30 vs payment on receipt

For 95 percent of UK independent workshops doing retail work, "payment on receipt of invoice / collection of vehicle" is the right answer. You finish the work, you generate the invoice, the customer pays. Done.

For trade work, Net 14 is typical. Net 30 is generous and only worth offering to large fleet accounts where the volume justifies the cash flow hit. Net 60 or anything longer is a red flag, decline politely.

How Autera handles the legal must-haves

Every invoice Autera generates includes:

• Workshop name, address, phone, email (set once in Settings)
• VAT registration number (if you have entered one)
• Sequential invoice number (auto-incremented, never duplicated)
• Invoice date and due date
• Line-by-line breakdown of parts and labour
• Net subtotal, VAT amount, gross total
• Payment instructions (card link if Stripe is connected, sort code and account number if not)

If you are not VAT registered, leaving the VAT registration number blank in Settings hides the VAT line entirely. No accidental VAT charges.

For payment terms, you set the default Net X days in Settings and override per invoice as needed.

I would rather build software that quietly does the right thing than ship one that lets owners accidentally break HMRC rules. The cost of a VAT correction is several hours with an accountant and a fine for repeat offences. The cost of doing it right from day one is zero.

A note on credit notes

If you need to refund or partially refund an invoice, do not delete the original. UK accounting practice (and HMRC) require a credit note: a separate document referencing the original invoice, with its own sequential number, showing the amount being credited.

Most workshop tools (including Autera) generate credit notes as a one-click action from a paid invoice. If your current tool just lets you "edit" or "delete" a paid invoice, that is an audit trail problem waiting to happen.

Free invoice template

If you are not ready for software and want a clean invoice to start from, search "HMRC simplified invoice template" on the gov.uk site. They publish a Word and Excel version that includes every legal field. It is not pretty but it is correct.

Or start free on Autera and you get a properly-formatted invoice on every job, automatically, in under 30 seconds.

When you outgrow Word and Excel

The honest answer: when you have more than about 20 jobs a month. Below that, a spreadsheet and Word template is fine and you do not need to pay for software.

Above that, the cost of mistakes (missed invoices, duplicate numbers, lost VAT records, customer-chasing time) crosses the cost of a £29 to £79 a month subscription quickly. The break-even point is usually one or two hours of admin time saved per week.

Autera handles all of this automatically. Try free for 14 days → or read about the founding-member offer (25 percent off forever, locked in).