What percentage window tint is legal in the UK?

On vehicles first used on or after 1 April 1985 the windscreen must let through at least 75% of light and the front side windows at least 70%. On older vehicles 70% applies to both. Going below either figure is a major defect and a failure, and film that looks light to the eye can still be below the limit.

Are tinted rear windows legal in the UK?

Yes. Windows behind the driver can be tinted as dark as you like, which is why factory privacy glass passes without difficulty. The light transmission limits apply only to the windscreen and the front side windows, and that is exactly why film applied at home to the front doors so often fails the test.

What happens if my window tint is too dark?

It is a major defect at the MOT, and the police can measure it at the roadside with a light meter quite independently of the test. That can end with a prohibition notice requiring the film to be removed before the vehicle is used again. Over-dark front windows are also a genuine hazard at dusk and at night.

How much does it cost to replace a car door window?

A door glass on a mainstream car is £70 to £160 fitted by a mobile glazier, and a rear quarter or tailgate glass £120 to £250. Professional tint removal is £30 to £60 per window. Check the insurance policy first, because glass claims usually carry a lower excess and often do not affect the no-claims discount.

MOT defect file

Window glass damaged or too heavily tinted

Last updated 27 July 2026

Quick answer

Glass other than the windscreen is cracked, shattered or tinted too dark. What counts is whether it affects the driver's view of the road, and how much light the front glass lets through.

Typical cost: £70–£350
DIY viability: Garage job

Viewed from in front of a right-hand-drive car, Zone A is on the right: it is the 290 mm-wide strip centred on the steering wheel within the wiper sweep. Damage over 10 mm in Zone A, or over 40 mm in the rest of the swept area, fails. Zone widths and chip sizes are exaggerated for clarity.

What you might notice

A cracked or shattered side or rear window, often held together only by the tint film over it
A rear view that is dark, hazy or distorted enough that you rely on the door mirrors instead
Bubbling, purpling or peeling aftermarket film on the front side windows
Missing glass replaced with a taped panel or a plastic sheet after a break-in

What causes it

A break-in or an attempted one, leaving toughened glass shattered into fragments
A stone or debris strike on a side window, which shatters rather than chips because the glass is toughened rather than laminated
Aftermarket tint film applied to the front side windows, which very commonly takes them below the legal transmission figure
Age and delamination on older glass, or a heated rear window whose element and film have degraded together

Advisory or failure?

Two separate things are assessed here. Damage to glazing is a defect where it affects the driver's view of the road — so a shattered driver's door window or a rear window that blocks the view through the interior mirror is a major defect, while damage to a rear side window on a car that meets its mirror requirement without it is usually not. Glass with sharp edges likely to cause injury is a major defect in its own right. Tint is a numbers test: on vehicles first used on or after 1 April 1985 the windscreen must let through at least 75% of light and the front side windows at least 70%, with 70% applying to both on older vehicles. How a breach is graded depends on its effect — excessive tint that seriously affects the view through the swept area or of an obligatory mirror is a major defect and a failure, while excessive tint that does not adversely affect the driver's view is only a minor defect, so the car passes with it recorded. Being under the limit is still an offence on the road whatever the tester writes down, and the police can test it at the roadside. Windows behind the driver can legally be tinted as dark as you like, which is why factory privacy glass passes without difficulty and a home-applied film on the front doors so often does not.

Can you fix it yourself?

Garage job

A door glass replacement means stripping the door card, dealing with a regulator that is often bonded or clamped to the glass, and vacuuming several thousand fragments out of the door cavity and the seat rails. It is achievable if you are patient and have the trim clips to hand, but a mobile glazier does it in under an hour and usually for less than the parts alone cost you. Tint film removal is the one part genuinely worth attempting: steam or a heat gun, patience, and an adhesive remover, working from a lifted corner. Test the result with a meter rather than by eye if you can, because film that looks light can still fail, and a glazier or a tint specialist will measure it for you.

What it costs

A door glass on a mainstream car is £70 to £160 fitted by a mobile glazier, and a rear quarter or tailgate glass £120 to £250. Heated, laminated, acoustic and privacy glass all cost more, and a heated rear window on a large estate or an SUV can exceed the top of the band on its own. Professional tint removal is £30 to £60 per window, more where the film has been on for a decade and comes off in flakes. Check the insurance policy before paying: glass claims usually carry a lower excess than a standard claim and often do not affect the no-claims discount, and a break-in claim may cover the interior clean-up as well.

What happens if you ignore it

A shattered window is an open car, so the immediate cost is usually the second break-in rather than the glass. Fragments left in the door drop into the regulator mechanism and jam it, turning a glass replacement into a glass and regulator job. Over-dark front windows are a genuine hazard at night and at dusk, where they hide pedestrians and cyclists you would otherwise have seen, and they attract police attention independently of the MOT — a roadside light meter test can end with a prohibition notice requiring the film to be removed before the vehicle is used again.

Common questions

What percentage window tint is legal in the UK?: On vehicles first used on or after 1 April 1985 the windscreen must let through at least 75% of light and the front side windows at least 70%. On older vehicles 70% applies to both. Going below either figure is a major defect and a failure, and film that looks light to the eye can still be below the limit.
Are tinted rear windows legal in the UK?: Yes. Windows behind the driver can be tinted as dark as you like, which is why factory privacy glass passes without difficulty. The light transmission limits apply only to the windscreen and the front side windows, and that is exactly why film applied at home to the front doors so often fails the test.
What happens if my window tint is too dark?: It is a major defect at the MOT, and the police can measure it at the roadside with a light meter quite independently of the test. That can end with a prohibition notice requiring the film to be removed before the vehicle is used again. Over-dark front windows are also a genuine hazard at dusk and at night.
Is a smashed side window an MOT failure?: It depends where it is. Damage to glazing is a defect where it affects the driver's view of the road, so a shattered driver's door window, or a rear window that blocks the view through the interior mirror, is a major defect. Glass with sharp edges likely to cause injury is a major defect in its own right.
How much does it cost to replace a car door window?: A door glass on a mainstream car is £70 to £160 fitted by a mobile glazier, and a rear quarter or tailgate glass £120 to £250. Professional tint removal is £30 to £60 per window. Check the insurance policy first, because glass claims usually carry a lower excess and often do not affect the no-claims discount.

The warning light behind this

This defect is what a tester writes down. What you see from the driver’s seat is a symbol, and it is worth checking which one, because manufacturers reuse the same shape for more than one system.

Washer fluid warning lightWhat it means and whether you can keep driving

This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.

Has this been recorded on your car?

Check the full MOT history for any UK registration.