Guides for traders.
Straight facts for buying and selling used cars, each one linked to where it comes from.
Write-off categories explained→
What the insurance write-off categories A, B, S and N mean, what happened to Cat C and Cat D in 2017, and what each category means for the log book and getting the car back on the road.
Facts checked on 12 October 2026
What is a Cat S car?→
Cat S means an insurer wrote the car off after structural damage, but it can be repaired. What that means for the log book, getting it back on the road, and buying or selling one.
Facts checked on 12 October 2026
What is a Cat N car?→
Cat N means an insurer wrote the car off after damage that wasn't structural, and it can be repaired. What that means for the log book, getting it back on the road, and buying or selling one.
Facts checked on 12 October 2026
Sold as seen→
What the law says when you buy a car from a private seller, sell it on to a consumer as a trader, or sell trade to trade — and what "sold as seen" does and doesn't change.
Facts checked on 12 October 2026
Car flipping in the UK→
Buying cars to sell on for a profit: when HMRC sees it as trading, the £1,000 allowance, Self Assessment, VAT and the margin scheme, trade plates, and your duties to buyers.
Facts checked on 12 October 2026
Where dealers get their stock→
The main ways UK used car dealers buy stock — auctions, part-exchange, other traders, online platforms and private sellers — and what the law and the numbers say about each.
Facts checked on 12 October 2026
Reading an MOT history→
What an MOT history shows for each test, what dangerous, major, minor and advisory mean, how far back the records go, how mileage and its unit are recorded, and the 2020 six-month extension.
Facts checked on 12 October 2026
Private sellers. One list.
Motorwatchr gathers private-seller cars from the big UK sites into one list every morning — with MOT history and the link to each advert.