Dirty plates can cost drivers dearly

Neil Hutchinson says one of the most common winter driving offences can be easily avoided

Motorists are being warned they could face fines of up to £1,000 if their number plates become too dirty to read, with wet and muddy winter conditions making it an easy mistake to overlook.

Under UK law, registration plates must be kept clean, visible, and legible at all times. If plates are obscured by grime, road salt, spray, or slush, police can issue an on the spot fine. In more serious cases, the offence can be taken to court, where the maximum penalty is £1,000.

In some parts of the UK, rain has fallen for more than 40 consecutive days from January into early February, suggesting that the bad weather is far from over.

It takes seconds to wipe your plates, but failing to do it could cost you hundreds. We see so many cars where the plates are completely unreadable after a week of rain and mud. Most drivers don’t even realise it’s against the law, but if the police can’t read your number plate, that’s a fine waiting to happen.

A dirty or unreadable plate isn’t just about avoiding a fine. It can also mean your vehicle fails its MOT and your car may trigger alerts on automatic number-plate recognition (ANPR) cameras used for policing and traffic enforcement. 

Simple checks drivers often overlook

• Make it part of your winter pre-journey routine: Before you set off, take 30 seconds to wipe the front and rear plate. It’s simple and reduces risk. 
• Watch for hidden obstructions: Think about rear bike racks, dirty covers, or even excessive mud splash. These can partially obscure plates and trigger enforcement. 
• Consider plate illumination: Even a clean plate can be unreadable at night if the light is dim or broken. Make sure your rear number plate light works.
• Use quick-check tech: After parking in muddy or snowy conditions, snap a photo of the rear late with your phone from 10-15 metres. If it’s not clearly legible in the photo, police or cameras probably won’t be able to read it either. 
• Beware the ‘I’ll clean it later’ trap: Delaying cleaning until the next wash day or until the car’s at the garage risks you already being stopped by officers. Police in some areas report dozens of stops for obscured plates in just a few days.

With rain, road spray, salt, and mud quickly building up during winter journeys, number plates that were clean earlier in the day can become unreadable in a matter of miles. Drivers are being urged to check their plates before every journey, as claiming you did not notice is unlikely to prevent a fine if you are pulled over.

Neil Hutchinson is founder of Mercury Car Centre