3D/4D Number Plate Laws: September 2021 and March 2022 Changes

2021 saw a number of unfounded concerns about the ongoing legality of 3D and 4D plates gain traction as the DVLA revisited their rules. The custom plate industry received lots of questions about what the changes meant.

Hot on the heels of the September 2021 changes came another set of requirements in March 2022. We understand that many people have found this confusing and have wondered if now a good time is to invest in 3D or 4D plates.

Let us put your minds at rest.

Here we’ll take a look at the 2021 law changes and how things have developed again since March 2022.

Print this legality form

With a lot more buying 4D plates we are having more and more people getting hassled by the police regarding the legalities behind them. Let’s be honest… when a lot of the officers that are on the road now were in training initially 4D plates was never really a thing. So we have created a form that you can print out and show to the officers if you were to get pulled just so they can get familiar with the law on these new variations of plates.

Hopefully this will make things a lot smoother for you guys that have purchased a legal 4D plate. Just save the image or print it out, keep it on your phone or in your glove compartment for easy access.


The short answer is YES. 3D plates and 4D plates are still legal. You can breathe a sigh of relief. Currently, characters on a number plate can 3D, so long as:

  • The number plate’s material is reflective
  • Front plate letters are black on white
  • Number plate characters must be of specific size and height
  • The must be 50mm wide, except for the number 1 or letter I
  • Spaces between them must be 11mm
  • There’s no background pattern
  • The rear plate letters are black on yellow
  • All the characters must be 79mm tall
  • The strokes on these black characters must be 14mm thick
  • There are other rules regarding character spacing and margins, which you can find in the DVLA’s INF104 leaflet.


The BSAU code on a number plate shows what standard the plate has been manufactured to:

  • BSAU 145d codes apply to plates manufactured BEFORE 1 September 2021
  • The old rules will continue to apply to BSAU 145d coded plates, BUT new rules will apply to BSAU 145e coded plates
  • BSAU 145e codes apply to plates manufactured AFTER 1 September 2021

Since September 2021, it’s been a requirement to check your number plate code to see if your number plate design is still within rules. This applies to 3D and 4D number plates too.

If your number plates were road legal at the time of purchase, they’ll still be legal providing they display the BSAU 145d code on the plate itself.

If you have a number plate made AFTER 1 September 2021, it will display the BS145e code and must follow the DVLA rules.

What changed for number plates in March 2022?

Three key changes came into force in March 2022 building on the number plate rules introduced in September 2021. These are:

Solid black font

To allow for easier vehicle identification by Automatic Number Plate Recognition systems, plates must have a solid black font. This, in effect, outlaws plates with 2D two-tone font that gives the impression of being 3D. Genuine raised 3D lettering is still permitted.

Plate durability

Plates now need to pass durability and toughness tests including an abrasion test. They have to be able to withstand grit, road salt and other debris while remaining readable. A BS AU 145e plate subjected to consistent force, as long as the adhesive pads are correctly placed, should take a minimum of 160 hours to remove.

Extra information

Newly registered plates are now required to display the supplier’s name and postcode, the BS AU 145e code and the name of the plate manufacturer.

Keep Up with Number Plate Changes

The world of number plates keeps on changing.

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