UK Tint Law
If you’ve got tinted vehicle windows, the front windscreen must let at least 75% of light through and the front side windows 70.
There are no rules for tinting the rear windscreen or rear passenger windows.
It is also illegal to sell a vehicle with heavily tinted windscreen and front windows.
Penalties for having wrongly tinted windows
The Window tinting Regulation was amended from 1st January 2004 which now clearly rules out any tinted films being applied to driver windows (Front doors).
The Regulation states 70% of visible light must pass through the driver's side windows (75% through the windscreen) including any other substrate fitted to the glass. Many people misunderstand the regulation and presume that 70% allows a 30% tint - It doesn't! Glass does not let in 100% of light. Clear glass only allows approximately 86% of light to pass & the slight tint of standard manufactured glass varies from the 70% maximum limit up to approx 80% of light passing through, thus any film being applied to these windows will drop the light transmissions to below the regulation limit.
If your front windows are tinted to any level you do risk being stopped by either Traffic Police or VOSA (Vehicle & Operator Services Agency) they have light meters to test the light that passes through your glass. If you have a subtle tint fitted then you should just be asked for it to be removed, if you have dark front door windows you could be told you can't drive your car any further and face a fine and points on your licence!
The police or VOSA vehicle examiners use light measuring equipment to measure window tint.
If your windscreen or front side windows are tinted too much you could get:
a ‘prohibition notice’ stopping you using your vehicle on the road until you have the extra tint removed
a penalty notice or court summons