If you only learn one number plate rule, make it this one. Since 1 September 2021, the characters on a UK number plate must be a single solid shade of black. That single sentence decides the legality of most of the styled plates sold online, and it is the fastest way to judge a product listing before you buy.
What the rule actually says
British Standard BS AU 145e requires that registration characters are black, that they are not reflective and that they are not removable. Black here means one uniform tone across the whole character. No gradients. No second shade of grey. No clear or coloured resin. No metallic or carbon finish.
Nothing in the rule bans depth. Characters can be raised, domed, layered or laser cut. What they cannot be is more than one colour.
Why a single shade matters
Automatic number plate recognition works by contrast. The camera sees a bright reflective background and a dark character shape, then matches that shape against a known character set. Anything that softens or varies that contrast makes recognition less reliable.
Two tone shadow fonts were the specific problem that prompted the rule. They print a lighter grey offset behind each character to imitate a three dimensional effect. To a human eye at two metres it looks like depth. To a camera at forty metres in the rain it looks like a smeared character outline.
Which plate styles the rule bans
- Printed shadow or two tone fonts. Banned. The grey offset is a second shade.
- Krystal and clear resin characters. Banned. Translucent sections are not solid black.
- Neon and coloured infill characters. Banned.
- Carbon fibre effect characters. Banned. The weave pattern creates multiple tones.
- Chrome or metallic characters. Banned, and also reflective, which breaks a second rule.
- Glitter or flake finishes. Banned.
Which styles the rule allows
- Standard flat printed black characters. Our standard plates.
- 3D gel domed characters in solid black. Our 3D gel plates.
- 4D laser cut acrylic in solid black, in 3mm or 5mm. Our 4D plates.
- Layered acrylic and gel combinations in solid black. Our 5D plates.
The gloss question
A common worry is whether a glossy gel character counts as reflective. Gloss and retroreflectivity are different things. Retroreflective material bounces light straight back to its source, which is what the plate background does deliberately. A glossy black character simply has a shiny surface finish. Solid black gel characters are currently viewed by the DVLA as acceptable under BS AU 145e.
How to check a plate in ten seconds
- Take the plate outside in daylight, not under a showroom light.
- Look at a character straight on. It should be one flat black from edge to edge.
- Look at the same character from an angle. No colour should appear in the edges or the top face.
- Check that no lighter outline, halo or offset shadow has been printed behind the character.
- Confirm the BS AU 145e marking, manufacturer identifier and supplier postcode are present.
What happens if your plates break the rule
A fine of up to £1,000, an MOT failure, and the possibility of a registration being withdrawn in serious cases. Enforcement of plate rules has been tightening, and the roadside check is simple for an officer to perform.
Frequently asked questions
Is dark grey acceptable?
No. The requirement is black, and a grey character would be treated as non compliant.
Does the rule apply to the border?
No. The single shade black rule applies to the registration characters. Borders and flags are governed by separate rules about obscuring the registration and the required markings.
Do older plates need to be changed?
Plates fitted on or before 31 August 2021 to the previous BS AU 145d standard can remain on the vehicle. Any plate you buy today must meet BS AU 145e.
Does the rule apply to show plates?
Show plates are display items sold for exhibition and collection use, and they are not road legal. The single shade black rule applies to every plate fitted to a vehicle used on a public road.
One rule, easy to follow
Every road plate we manufacture uses solid black characters and is made to BS AU 145e. If you are unsure about a design, send us a message and we will tell you straight whether it is road legal.