How Can a Number Plate Fail an MOT?

When preparing your car for its annual MOT, the number plate might not be something you consider – but it should be.

14% of MOT failures are due to number plate issues, ranging from dirt and damage to non-compliance with legal standards. This highlights the need to be weary that your number plate should be in full compliance heading in to your MOT test.

In this guide, we’ll explain exactly how a number plate can cause an MOT failure, what the official DVSA rules are, and what steps you should take if your number plate fails the test.
 

Can You Fail an MOT Because of a Number Plate?

Yes, you absolutely can. The Driver and Vehicle Standards Agency (DVSA) includes number plate checks as a key part of the MOT test.

If your plate is missing, obscured, incorrectly formatted, or poorly lit, your vehicle could be marked with a major defect, resulting in an MOT failure.

MOT testers inspect both front and rear number plates to ensure they meet UK regulations.

These plates must be:

• Correctly formatted with the legal UK registration
• Clean and clearly legible
• Properly secured
• Free of damage or delamination
• Illuminated (rear plate) with a functioning white light

Failing to meet any of these standards could see your vehicle fail its MOT.

Common Number Plate Issues That Can Cause an MOT Failure

1. Cracked or Damaged Number Plates

A cracked, chipped, delaminated or bent number plate is one of the most frequent causes of MOT failures related to plates.

If the damage affects the legibility of the characters or reflects poorly under lighting, it can be marked as a major defect.

Tip: If your number plate is damaged – even slightly – consider replacing it before your test to avoid a fail.
 

2. Dirty or Obscured Plates

Dirt, mud, or snow that obscures the characters on your plate can also result in a failure.

Plates must be readable at all times, both to MOT inspectors and to ANPR (Automatic Number Plate Recognition) systems used by police.

Tip: Give your plates a quick clean before the MOT. It’s a simple fix that could save you hassle.
 

3. Number Plate Light Not Working

For vehicles registered after 1^st January 1973, the rear number plate must be illuminated with a white light.

A blown bulb or faulty light unit is enough to fail the MOT.

Important: The light must be white – coloured or flashing lights are illegal and could incur a fine of up to £1,000, alongside failing your test.
 

4. Missing Number Plates

This is one of the most clear-cut reasons for failure. A missing front or rear plate will result in a major defect, rendering your vehicle unroadworthy until fixed.
 

5. Non-Standard or Illegal Number Plates (UK)

While private plates are legal, they must comply with DVLA regulations. A non-standard plate could fail your MOT if it:

• Shows the wrong registration number
• Has background overprinting or patterns (e.g. honeycomb effect)
• Features italic or incorrectly spaced characters
• Has tints or coloured films that obscure the letters
• Uses screws or fixings that alter the appearance of characters

Summary of Number Plate Major Defects for MOT Tests

To summarise from the above number plate issues, the following are what will cause an automatic MOT failure:

• Number plate is missing or insecure
• Characters are illegible, missing or obscured
• Registration is incorrect
• The plate does not conform to DVLA requirements
• The plate has damaging overprinting, such as reflective designs or honeycomb effects (vehicles first registered from 1^st September 2001 onwards)

These are all classed as major defects, meaning the vehicle cannot pass until the issue is resolved.
 

What Happens If Your Car Fails Its MOT Due to the Number Plate?

If your car fails its MOT because of a number plate issue, you’ll be issued a VT30 refusal certificate. The failure must be corrected before the vehicle can be retested.

Many garages will allow a free retest within 10 working days if the repair is minor and completed quickly. Some may even replace a faulty bulb or help secure a loose plate during the initial visit, depending on the fault and garage policy.

For plate-related issues like cracks or illegibility, you’ll need to buy a new number plate. Prices typically start around £15-£20 and you can get one printed at an approved local garage.
 

How to Replace a Number Plate

To replace your number plate legally, you’ll need to:

• Provide proof of ID (e.g. a driving licence)
• Provide proof of entitlement (e.g. V5C logbook or retention certificate)
• Visit a certified number plate supplier

Make sure the new plate is fully compliant with DVLA guidelines to avoid further issues.
 

How to Check When Your MOT Is Due

If you’re unsure when your MOT is scheduled, use GOV.UK’s online MOT checker tool.

Simply enter your registration number to find out the test expiry date and start preparing early.
 

Final Thoughts

Failing your MOT due to a number plate issue might seem minor, but the consequences can be major.

Fortunately, most problems – like a dirty or cracked plate – are simple and inexpensive to fix.

Whether you’re running a standard plate or a personalised registration, ensuring it’s readable, correctly formatted, well lit, and undamaged is essential for a smooth MOT pass.