Cat S and Cat N: what each write-off category actually permits

A Cat N car can change hands with a log book that looks completely ordinary. A Cat S car cannot. That one difference decides how much work you have to do before you buy either of them.

Most guides to the UK write-off categories open with the four letters. The four letters are the easy part. They sit in a table on GOV.UK that takes ten seconds to read. What actually matters, to anyone buying damaged stock or weighing up a cheap car with a history, is what each category does to the paperwork, what it leaves untouched, and the fact that none of it is law.

The four categories, in the government’s own words

GOV.UK publishes the categories as a table with three columns, and the table is the whole of it. There is no prose definition anywhere on the page.

Read the right-hand column again. For N and S it is the same sentence, word for word. The government draws no distinction at all between what you may do with a repaired Cat S car and a repaired Cat N car. The difference is entirely in the left-hand column, and it is a description of the damage, not of the permission.

That is worth holding onto, because almost every piece of advice written about these categories treats Cat S as a lesser class of car that is allowed back on the road under sufferance. The published rule says nothing of the kind.

There is no law behind any of this

This is the part that surprises people, and the ABI says it in plain English rather than leaving it to be inferred:

The Salvage Code of Practice is a voluntary code which was brought about by the ABI because there is no regulation relating to written-off vehicles.

The same statement goes further and says the ABI is still campaigning to change that:

All ABI member motor insurers support the Salvage Code of Practice and adhere to its provisions. We continue to call for the Salvage Code to be put in statutory footing.

So the letter attached to a car was assigned by an insurance company, applying a code that the insurance industry wrote for itself, which no regulator enforces. The ABI explains what the code is for: it “helps ensure that unsafe vehicles and parts are not put back onto our roads.”

And it is candid about why a car ends up categorised in the first place:

Typically, a vehicle is deemed a total loss when a repair is uneconomical, or unviable from a safety perspective.

Uneconomical, or unsafe. Those are two completely different cars wearing the same letter. The ABI spells out the consequence itself: “When an insurer deems a vehicle as a total loss for financial reasons, rather than because it is unsafe, it would be a waste to crush it.”

The practical consequence: a category tells you an insurer declined to pay for the repair. It does not tell you the car was dangerous, and it does not tell you the car was fine. You still have to look at the car.

Cat S is written into the log book. Cat N is not.

Here is where the two repairable categories stop being twins. GOV.UK’s instructions for keeping your own written-off car are split, and the split is sharp.

For both, the starting point is the same: “If you want to keep a vehicle in category N or S, the insurance company will give you an insurance payout and sell the vehicle back to you.”

Then category S picks up two extra steps. You must “send the complete log book to your insurance company” and “apply for a free duplicate log book using form V62”. And then the line that matters to every future buyer of that car:

DVLA will record the vehicle’s category in the log book.

Category N gets one sentence instead:

You can keep the log book if you want to keep a category N vehicle.

No surrender, no V62, no new document, and nothing on the page about DVLA recording anything.

The practical consequence: on a Cat S car the V5C does your work for you. On a Cat N car the V5C is not evidence of anything. The document in the seller’s hand can look exactly like the document for a car that has never been claimed on. If your buying process is “the log book looked fine”, you have no process for Cat N at all.

This is the mirror image of the American system, where the state writes the status onto the title itself and it stays there. Virginia, for one, states that the brand “is permanent and will carry forward to each title issued for the life of the vehicle.” Salvage title vs rebuilt title runs that sequence in full, and the contrast is useful: the US puts the history in the document, the UK puts half of it there.

What the published rules do not say

It is worth being precise about the size of the gap, because filling it with assumptions is how traders lose money.

GOV.UK’s write-off pages do not say:

• what counts as structural damage, or where the line sits
• who decides whether a repair reached “roadworthy condition”
• that any test, inspection or identity check is required before the car returns to the road
• that the category stays on the vehicle’s record permanently
• anything at all about removing a category

The entire published standard for putting a repaired Cat S or Cat N car back on the road is five words: “repaired to a roadworthy condition.” The page names no inspection and nobody who signs it off.

That is not an oversight in the writing. It follows directly from the first point in this article. There is no regulation, so there is no regulator to specify a test.

Why the 2025 update matters more than it sounds

In August 2025 the ABI announced an update to the code, and included a detail that puts the previous six years in perspective:

The Code was last updated in 2019.

What changed is squarely aimed at what the UK fleet has become since:

The updated Salvage Code of Practice now brings electric and hybrid vehicles within its guidance, and considers megacasting, reusable parts, and other advanced vehicle construction methods.

The ABI defines megacasting in a footnote as “a process in vehicle manufacturing for producing large metal parts using high-pressure die casting (HPDC).” It also notes “improved wording for different vehicle types, such as Heavy Goods Vehicles and motorcycles”, and that the work was done with “insurers, the Motor Insurers’ Bureau (MIB), and Thatcham Research”.

Mark Shepherd, the ABI’s Head of General Insurance Policy, framed it this way: “It’s important the code moves with the times, and this update reflects the increasing sophistication of our vehicles, including new powertrains and construction methods.”

The practical consequence: every electric car written off in the UK between 2019 and 2025 was categorised under a code that did not address electric cars, and every car with a large cast structure was categorised under a code that did not mention the method. If you are looking at a damaged EV with a 2021 or 2022 category on it, the letter was assigned under rules that have since been judged incomplete by the body that wrote them.

Buying one to put back on the road

The trade case for repairable write-offs has not changed: fewer buyers compete for them, so you buy cheaper. The risk has not changed either, and it is rarely the risk people expect.

The purchase price is the smallest number in the deal. Parts, labour, paint, transport to and from the bodyshop, an MOT, storage while it waits for a part, and the weeks it sits unsold afterwards all land on the same car. On a repaired write-off those lines are bigger and more numerous than on ordinary stock, which is exactly why the margin looks better on paper than it turns out to be. The true cost of a car covers where those lines usually go missing, and gross profit per car covers the difference between the margin you think you made and the one you actually made.

Then there is the exit. Your buyer will run a history check whether or not the V5C says anything, and a Cat S car arrives at that conversation with the category printed in the document. That is not a reason to avoid them. It is a reason to price the car on what a categorised example of that model actually sold for, not on what a clean one is advertised at. It also tends to sit longer, and days on the lot covers what waiting does to the return on a deal.

Get the buying price and the cost tracking right and categorised stock is one of the better margins available to a small trader, for the simple reason that most of your competitors will not touch it. Get the cost tracking wrong and a car that looks like it made £2,000 made £700.

Telling DVLA, and the £1,000 fine

If you are the registered keeper when a car is written off, there is one obligation that is easy to miss and expensive to miss.

You must tell DVLA if your vehicle has been written off and scrapped by your insurance company.

GOV.UK frames the transaction in a way that makes the rest of it make sense: “Writing off and scrapping your vehicle is the same as selling it to your insurance company.” You report it like a sale to the trade, using “the 11 digit reference number from the yellow ‘sell, transfer or part-exchange your vehicle to the motor trade’ section of the log book (V5C)”. The service runs “from 7am to 7pm”, and afterwards you “destroy the yellow ‘sell, transfer or part-exchange’ section of the log book” rather than posting it in.

The penalty line appears on both the write-off page and the scrapping guide, in the same words each time:

You can be fined £1,000 if you do not tell DVLA.

How to actually check a car

Pulling the published facts together gives a short list that does not depend on anyone’s opinion.

1. Treat the V5C as evidence for Cat S only. It carries the category on an S car and tells you nothing on an N car.
2. Run a history check on every car, not the suspicious ones. That is the only step that sees a Cat N marker.
3. Ask which half of the ABI’s sentence applies. Uneconomical or unsafe. The insurer’s reason is the single most useful thing you can learn, and the seller may actually know it.
4. Check when the category was assigned. Anything before the 2025 update, and particularly an EV, was categorised under a code the ABI has since rewritten.
5. Price from sold examples of categorised cars, not from clean asking prices.
6. Put every cost on the car, as it happens. This is the step that decides whether the deal was good, and it is the one most traders reconstruct from memory weeks later.

The categories are a useful signal and a poor verdict. A Cat N car with a straight shell and a replaced wing is a different proposition from a Cat S car with a kinked chassis leg, and the letters alone will not tell you which one is in front of you. The published rules are thinner than most people assume, and knowing exactly where they stop is what separates a trader who buys these well from one who gets caught by them.