MOT Fees 2026: Test, Retest, Diagnostic & Late Fees Breakdown

The retest rules are some of the most under-used cost-saving devices in the MOT system. The headlines:

Same garage, within 10 working days, partial retest = free. Only the items that failed are re-checked. If you fix them and bring the car back inside 10 working days, the garage rebooks for a partial retest at no charge. The 10-day clock starts the next working day after the original test, not the same day.

Same garage, overnight, full retest = free. If you leave the car overnight for repair work at the testing garage, the next-day retest is free. This is the more practical option for fails that need parts ordered.

Different garage = pay full Class 4 fee again. No discount, no portability. The new garage starts a fresh full test.

The free retest at the same garage can be re-failed if items not originally on the fail list have deteriorated since the first test. This rarely happens within 10 days but is technically allowed. More detail on the MOT retest cost page.

A diagnostic fee covers fault-finding work that goes beyond the standard MOT check. It is legitimate when:

• The garage has identified an unknown fault that requires plugging in a diagnostic computer (engine management light, ABS fault, intermittent electrical issue).
• The fee is quoted before work begins and you authorise it in writing or by text.
• The garage delivers an itemised report explaining what was found.

It is not legitimate when:

• The fee is added to the bill without prior agreement.
• The "diagnostic" was actually a standard MOT visual check.
• No written report is provided.

Typical 2026 diagnostic fees: £20-50 at an independent, £40-90 at a main dealer. The higher figure usually reflects 30-60 minutes of qualified technician time on a manufacturer-specific diagnostic platform.

The Road Traffic Act 1988 makes it an offence to use a vehicle on a public road without a valid MOT certificate. The fees and penalties are:

Fixed Penalty Notice (FPN): £100. Issued if stopped by a police officer or flagged by ANPR. Carries no licence points unless the vehicle is in a clearly dangerous state.

Court fine: up to £1,000. Higher fine available if the case goes to court rather than being resolved by FPN.

Insurance implications. Most insurance policies become invalid in the absence of a current MOT, which means any claim while uninsured by extension. Third-party-only cover for damage to others usually remains active under statute but your own car, theft, fire and other claims will be rejected. Full detail on the MOT insurance implications page.

One exemption. You may drive a vehicle without a current MOT to a pre-booked MOT appointment or to a garage for arranged repair work. You must be able to demonstrate the booking if stopped.