What Are Illegal Number Plates in the UK? (And How to Avoid a £1,000 Fine)

Quick Answer

Illegal number plates include those with the wrong font, incorrect spacing, tinted covers, non-standard backgrounds, or supplied by an unregistered supplier. The penalty is up to £1,000 and an automatic MOT failure. All Car Plates Pro plates are fully road-legal.

Illegal number plates in the UK are any plates that do not meet British Standard BS AU 145e, use a non-standard font, display incorrect character spacing, carry a tinted cover, or were supplied by a seller not registered with the DVLA. Driving with illegal plates carries a fine of up to £1,000 and will cause an MOT failure.

This guide explains exactly what makes a number plate illegal in the UK and what you need to check before fitting plates to your vehicle.

The Wrong Font

The only font permitted on a UK road-legal number plate is Charles Wright 2001. This is the font specified in BS AU 145e. Any plate using a different typeface, including italic versions, condensed variants, or custom fonts designed to look stylish or resemble letters in a name, is illegal for road use.

The Charles Wright 2001 font has specific stroke widths and proportions that make each character instantly readable at speed by both human observers and ANPR cameras. Deviating from it for any reason makes the plate non-compliant.

Incorrect Character Spacing

UK number plates must use the exact spacing prescribed by BS AU 145e: 11mm between individual characters, 33mm between the two groups of characters in the registration. Deliberately altering this spacing to make the registration spell a name or word is illegal and is one of the most common reasons drivers receive £1,000 fines.

For example, displaying “S1 MON” as “SIMON” by removing the gap between the groups is a specific offence. Even a seemingly minor adjustment to spacing can result in a fine.

Tinted or Smoked Number Plate Covers

Transparent or tinted covers placed over number plates became explicitly illegal under the September 2021 update to BS AU 145e. Even a lightly tinted cover can reduce the retroreflectivity of the plate and interfere with ANPR cameras. Removing covers is a simple fix if you are driving with them fitted.

Non-Reflective Backgrounds

Front plates must have a white reflective background and rear plates must have a yellow reflective background. Matt, painted, or non-reflective backgrounds do not meet the standard. The background must contain the appropriate level of retroreflectivity as specified in BS AU 145e.

Missing Supplier Identification

Every road-legal number plate must carry a permanent marking on the reverse identifying the DVLA-registered supplier. Plates without this marking were either not made by a registered supplier, or the marking has been removed. Both are illegal.

Plates from Unregistered Suppliers

Only DVLA-registered number plate suppliers (RNPS) are permitted to manufacture and sell road-legal number plates. Unregistered suppliers do not carry out the required identity checks, and their plates typically do not meet BS AU 145e even if they appear similar to compliant plates. Buying from an unregistered supplier is a legal risk and is an offence for the seller.

Car Plates Pro is a DVLA-registered supplier. Every plate is BS AU 145e certified. Build your plates here.

Show Plates Fitted to Road Vehicles

Show plates are manufactured for display, photography, and off-road use only. They are not BS AU 145e certified and must never be fitted to a vehicle driven on public roads. If show plates are found on a road-driven vehicle, both the driver and the supplier who sold them as road-legal may face prosecution.

Flags, Symbols, and Decorations

Number plates may display the national flag and identifier of England, Scotland, Wales, or the UK (GB) on the left-hand side. No other symbols, graphics, or decorations are permitted in the plate area. Coloured borders, patterns, or logos around the plate text are illegal.

Damaged and Unreadable Plates

A plate that is cracked, faded, missing characters, obscured by dirt, or otherwise unreadable is illegal for road use. Police officers, DVSA enforcement, and MOT testers can all cite unreadable plates as a reason to issue penalties or fail a vehicle.

Electric Vehicle Plate Rules

Electric vehicles may optionally display a green flash on the left-hand edge of both front and rear plates. This is the only colour variation permitted from the standard white-front, yellow-rear requirement. The green flash is not mandatory and does not change any of the other legal requirements.

What to Check on Your Plates

To confirm your plates are legal, check:

Purchased from a DVLA-registered supplier
Supplier marking visible on the reverse
Charles Wright 2001 font
Correct character spacing (11mm between characters, 33mm between groups)
White reflective front, yellow reflective rear
No tinted covers
No cracks, fading, or missing characters
No alterations or added decorations

Replacing Illegal Plates

If your current plates do not meet these standards, replace them before your next MOT or before driving again. Car Plates Pro dispatches plates the same day for orders placed before 2PM, with next working day delivery to 98% of UK addresses.