UK Number Plate Rules: What the Law Allows
A number plate is legal in the UK when the finished plate meets the British Standard, BS AU 145e, and is displayed the way the rules on GOV.UK require. Everything below follows from that one sentence: the colours, the font, the spacing, the markings along the bottom, and the long list of things people ask us for that we will not make. Nothing about the style of the characters decides it. What decides it is the finished plate.
This page answers the questions we are actually asked, in the order we are asked them. Each one links to a fuller answer where there is one.
What makes a number plate legal?
GOV.UK sets it out as a list. The plate must be made from a reflective material, display black characters on a white background at the front and a yellow background at the rear, carry no background pattern, be marked to show who supplied it, and be marked with a British Standard number, which is BS AU 145e for plates fitted after 1 September 2021. The characters must not be removable or reflective, and on plates fitted since that date they must be a single shade of black. The registration must be shown correctly: you cannot rearrange the letters or numbers, or alter them so they are hard to read.
Those are the rules a plate is judged against at the roadside and at an MOT. Why the front is white and the rear is yellow, and where black and silver plates fit in, is covered separately.
Can I have a slogan along the bottom?
No. The regulations start from the position that other than the registration itself, no additional markings may be displayed on a plate. The supplier name and postcode, the component maker and the British Standard number are the exception written into the rules, and they are required rather than optional. A slogan, a dealer name, a flag outside the permitted panel or a web address all take the plate outside the standard. What each part of the bottom text means is explained in full elsewhere.
Can I space the characters how I like?
No. The spacing is fixed by the regulations, not by taste: 11mm between characters within a group and 33mm between the two groups on a standard car plate, with 11mm margins. Closing that gap so a registration reads as a word or a name is the single most common reason a plate is pulled, because it changes what the registration says. The same applies to using a screw, a bolt cap or a badge to disguise a character: if the plate no longer shows the registration correctly, it is an offence however it was done.
Can I have tinted plates?
No, and no registered supplier can legally make you a set for the road. A tint sits over the reflective face and changes the background the registration is read against, so the plate can no longer meet the reflectivity the standard measures. A plate that cannot meet it cannot carry the BS AU 145e mark, and a plate without the mark is not legal to fit. Our full answer on tinted plates covers why a tint is nothing like a raised character.
Are coloured or crystal characters legal?
No. They are sold under names like neon, fluorescent, coloured and crystal, and they use coloured or translucent acrylic for the characters. The rules require the characters to be a single shade of black on a reflective background, so anything tinted, two-tone, shadowed within the character or coloured takes the plate outside the standard, however well it is made. Carbon fibre effect characters are out for the same reason: the finish is not a single shade of black.
Are 3D gel and 4D plates legal?
Yes, when the finished plate meets BS AU 145e. GOV.UK expressly allows plates to have 3D raised characters, and depth is not colour: a solid black acrylic character bonded to a compliant plate changes nothing the rules measure. That is the whole difference between a raised character, which is allowed, and a tint, which is not. Our guide to 3D and 4D legality goes through the standard and the proposed amendment to it, and the 4D range shows how they are built.
Can I have a shorter, square or import-shaped plate?
Shape is not what the rules fix. A shortened plate is legal as long as the character size, spacing and margins are unchanged, which is why a shortened plate is shorter rather than tighter. Square plates for 4x4s and motorbike plates work the same way, with their own sizes. Import shape plates are the exception that proves the rule: they use smaller characters, and that is only legal on an imported vehicle without European Community Whole Vehicle Type Approval whose plate recess will not take a standard plate.
Hex plates, cut with angled ends and sized to the registration, are legal for the same reason: the outline is not what the regulations specify.
Which flags and identifiers can I have?
One flag from a fixed list, with a national identifier beneath it, in the panel on the left-hand edge: the Union flag, the Cross of St George, the Saltire or the Red Dragon of Wales, with UK, GB, ENG, SCO, CYM or WALES. The flag must sit above the identifier, neither may sit on the plate margin, and neither may be more than 50mm wide. A zero-emission vehicle may also display a green flash in the same panel. Anything else in that space, including a regional flag or a badge, is not permitted.
Do I have to display a front plate?
Yes, on a car. Motorcycles and motor tricycles registered on or after 1 September 2001 display a rear plate only. For everything else the front plate is required, and running without one is the same offence as running an illegal one.
What about show plates?
A show plate is any plate that does not meet the standard, whether that is illegal spacing, a tint, a slogan or missing supplier text. They are for a stand at a show and not for the road, and they fail an MOT for the same reason they are not road legal. We do not make them in any form, including plates with adjusted spacing.
What does an illegal plate actually cost?
The roadside outcome is a £100 fixed penalty notice. GOV.UK publishes the ceiling: "You could be fined up to £1,000 and your vehicle will fail its MOT test if you drive with incorrectly displayed number plates." The £1,000 is the maximum a court can impose rather than the usual figure, and the MOT failure is the part that catches people out, because the vehicle is off the road until the plate is replaced. A registration that has been deliberately misrepresented can also be withdrawn.
How to be sure the plates you order are legal
Buy from a registered number plate supplier, which is a legal requirement rather than a preference: a supplier has to see documents proving who you are and that you are entitled to the registration before making anything. Order the registration exactly as it appears on the V5C, take the standard spacing, and choose a style rather than a modification. Every plate we make is built to BS AU 145e and carries our name, postcode and the standard mark, whichever style goes on top. You can see any of them on your own registration in the plate builder before ordering.
If you are choosing a registration rather than a plate, the private plates hub is the place to start.
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