How the MOT test works: what is checked and what the results mean
1 August 2026·5 min read
Who needs an MOT, and when
Every car in the UK needs an MOT before its third birthday, then once a year. The next due date is the one on your current certificate, not the date you bought the car. You can test up to a month early and keep the original expiry date.
Tests are done by DVSA-approved testers at authorised garages. Since 2019 there are no paper certificates. Every result goes straight to the official MOT history service, which is where Roadworthy gets its data.
What the tester actually checks
A class 4 test covers cars up to 3,000 kg and works through about 19 areas: lamps and reflectors, brakes, tyres and wheels, steering, suspension, exhaust and emissions, seatbelts, body and corrosion, and the vehicle identification plate.
A worn part does not always mean a fail. Testers record everything they see, but only defects that affect safety or emissions decide the result. The rest comes back as advisories, which are worth reading before you book any work.
- Brakes: condition, operation and performance, checked on rollers
- Tyres: at least 1.6mm across the central three-quarters, with no cuts or bulges
- Emissions: exhaust gas checked for CO, and smoke for diesels
- Body: serious corrosion in a load-bearing area fails on the spot
- Everyday basics: wipers, washers, horn and mirrors must work
The five results you can get
There are five outcomes. A pass means no fail-level defects. An advisory flags wear you can still drive with but should plan for. A minor is the old advisory under a new name and does not fail the car. A major fails the test, but you can drive away for repair. A dangerous means you cannot drive the car at all, and the tester must record it with the DVSA.
This five-way system replaced a single fail in 2018, so the same problem can read differently depending on when the test happened.
Retests and the free retest window
If the car fails, the same garage will usually retest free within 10 working days if it does the repairs. If you take the car elsewhere, you pay again, so it pays to price the work before you choose where to test.
A car with a major can be driven to a pre-booked repair and then to the retest. A dangerous cannot be driven anywhere and will need to be recovered.