What part of your car does the law actually require you to keep in good condition in 2026? Many drivers assume it’s just seat belts, especially from the UK driving theory test, but the reality is much broader.

In real-world driving, UK roadworthiness laws cover multiple essential components of your vehicle. So, what exactly are you responsible for maintaining?

Key parts that must always remain safe and functional include:

• Seat belts
• Tyres
• Brakes
• Lights and indicators
• Windscreen and wipers
• Mirrors
• Steering and suspension
• Exhaust and emissions
• Number plates

Failing to keep these in good condition isn’t just risky, it can lead to fines, penalty points, MOT failure, invalid insurance, or even prosecution.

So, what does the law actually require in 2026, and how can you stay compliant? Let’s break it down.

Why the Law Requires You to Keep Your Car in Good Condition?

The law requires your car to be in good condition because any vehicle can become dangerous if not properly maintained. Even small issues, like worn tyres, faulty lights, or damaged seat belts, can quickly lead to serious accidents.

UK roadworthiness rules are mainly based on the Road Traffic Act 1988 and the Road Vehicles (Construction and Use) Regulations 1986. These laws require every vehicle to be safe whenever it is used on public roads, regardless of ownership.

Many drivers assume that passing an MOT guarantees safety for a year. In reality, an MOT only confirms the vehicle met standards on the test day. If a fault develops later, the vehicle may still be illegal to drive.

The purpose of the law is to protect:

• Drivers and passengers
• Pedestrians and cyclists
• Other road users
• Emergency and road workers

Poor maintenance reduces control, increases stopping distance, and raises accident risk, especially in bad weather or heavy traffic.

What Can Happen If Your Car Is Not Kept in Good Condition?

Driving an unroadworthy vehicle can lead to more than a failed MOT. Police and enforcement teams like the Driver and Vehicle Standards Agency can stop vehicles at any time, and if your car is unsafe, you may face immediate penalties.

Some defects result in small fines, while others can lead to large penalties, licence points, or even a driving ban:

• Faulty headlight or brake light: £100 fine
• Dirty or unreadable number plate: up to £1,000 fine
• Illegal tyre: up to £2,500 fine + 3 penalty points (per tyre)

If all four tyres are below the legal tread depth, you could face:

• Up to £10,000 in fines
• 12 penalty points
• Possible driving disqualification

“Tyres remain one of the most common reasons for roadside checks because they are easy to inspect and critical for safety,” notes a senior officer from National Highways.

Insurance is another risk. If your vehicle is not roadworthy during an accident, your insurer may reduce or reject your claim, even if the defect did not directly cause the incident.

How to Avoid These Penalties?

Regular checks can help you stay compliant and prevent costly issues.

Weekly Checks

To reduce the risk of penalties, it is worth carrying out simple weekly checks. These only take a few minutes and can prevent expensive problems later.

• Check that all lights and indicators work
• Make sure your number plates are clean and readable
• Inspect tyre pressure
• Top up the washer fluid
• Test your windscreen wipers

Monthly Checks

Once a month, carry out a more detailed inspection.

• Measure tyre tread depth
• Inspect seat belts for fraying or damage
• Check mirrors for cracks
• Look for chips or cracks in the windscreen
• Listen for unusual noises from brakes or steering

Before a Long Journey

Before driving long distances, especially on motorways, carry out a full visual inspection of the vehicle. This is particularly important if you are travelling during winter or poor weather conditions.

A real-life example occurred in the early 2026 when a driver travelling from Birmingham to London was stopped on the M40 during a roadside inspection.

Officers found two tyres below the legal tread depth. The driver received six penalty points and a £5,000 fine for defects that could have been avoided with a simple pre-journey check.

How Can You Make Sure Your Car Always Meets Legal Standards?

Keeping your vehicle roadworthy doesn’t require specialist mechanical knowledge. Most legal issues can be avoided by staying proactive and fixing small faults early.

Regular servicing is one of the best ways to stay compliant. A mechanic can spot wear in areas you might miss, such as steering, suspension, and brakes.

You should also watch for warning signs. If your car pulls to one side, the steering feels loose, the brakes make unusual noises, or dashboard warning lights appear, don’t ignore them.

“Modern vehicles often provide early warning signs of faults. Drivers should never ignore dashboard alerts or changes in the way the car feels,” advises an RAC vehicle engineer.

It is also important to remember that legal responsibility rests with the driver. Even if you are using a hired car, a leased vehicle, or a friend’s car, you can still be fined if it is unsafe.

The table below shows who is legally responsible in different situations:

Keeping your car properly maintained and addressing issues early will help you stay compliant, avoid penalties, and ensure safer driving at all times.

What Part of the Car Does the Law Require You to Keep in Good Condition?

Although seat belts are the direct answer to the common theory test question, UK law requires several important parts of your vehicle to be maintained properly.

1. Seat Belts

Seat belts are the most important legal safety requirement and the expected answer in most driving theory tests.

Every seat belt in the car must work correctly, including those in the rear seats. Under UK law, the driver is responsible for making sure that passengers under the age of 14 are wearing a seat belt or a suitable child restraint.

A legal seat belt must:

• Fasten securely
• Retract properly
• Lock in place during sudden movement
• Be free from cuts, fraying, or other damage
• Have a buckle that clicks firmly into place
• Operate without sticking or jamming

If a seat belt is damaged or fails to operate correctly, the car will fail its MOT. You should also check that the dashboard seat belt warning light works correctly in newer vehicles.

I once spoke to a parent in Manchester who admitted they had ignored a sticking rear seat belt for several weeks because they thought it was “only a minor issue”. After being stopped by police, the driver said:

“I honestly thought it would not matter because the belt still looked fine. I had no idea that if it would not lock properly, I could be fined.”

Seat Belt Legal Requirements:

Keeping your seat belts in good condition is one of the simplest ways to stay legal and protect everyone inside the vehicle.

2. Tyres

Tyres are among the most heavily regulated parts of any vehicle. They are the only part of the car that touches the road, so even a small defect can affect braking, steering, and grip.

Tyres must meet the following legal standards:

• A minimum tread depth of 1.6mm across the central three-quarters of the tyre
• No cuts, bulges, exposed cords, or dangerous wear
• Correct size and type for your vehicle
• Correct tyre pressure according to the manufacturer’s recommendation
• Matching tyres on the same axle where required

Incorrect tyre pressure can make a vehicle unsafe. Underinflated tyres reduce fuel efficiency and increase stopping distances, while overinflated tyres reduce grip and make the vehicle harder to control.

Many drivers use the 20p test to check tread depth:

• Insert a 20p coin into the tyre tread
• If you can see the outer rim of the coin, the tread may be below the legal limit

Regular tyre checks are essential because even one illegal tyre can result in a fine of up to £2,500 and three penalty points.

3. Brakes

Your brakes must always be capable of stopping the car safely and evenly. If your vehicle pulls to one side when braking, makes grinding sounds, or has a soft brake pedal, there may be a serious problem.

The following are common warning signs that your brakes may need attention:

• Squealing or grinding noises
• A soft or spongy brake pedal
• Vibrations when braking
• The car is taking longer to stop
• The brake warning light appears on the dashboard
• The vehicle pulls to one side under braking

Brake defects are considered dangerous because they can lead to complete loss of control. In severe cases, police can prohibit you from driving the vehicle until repairs are carried out.

One London motorist experienced this in Camden during a roadside inspection. After the vehicle was checked, the driver said:

“The officer showed me how worn the brake pads were and told me I was lucky they had not failed completely. I could not believe I had been driving around like that.”

Brakes should never be ignored because a small problem can quickly become a serious safety issue.

4. Lights and Indicators

All exterior lights must work correctly at all times. This includes headlights, brake lights, indicators, rear lights, fog lamps, and number plate lights. These are essential not only for visibility but also for signalling your actions to other road users.

All exterior lights must work correctly. This includes:

• Headlights
• Brake lights
• Indicators
• Rear lights
• Fog lamps
• Number plate lights

These lights are essential not only for helping you see the road, but also for helping other road users understand your movements.

Lights must also be:

• Clean
• Properly aligned
• Clearly visible
• Free from cracks or broken covers

A misaligned headlight may dazzle other drivers, while a broken indicator makes it harder for others to predict your movements. Dirty light covers can also reduce visibility, especially during winter when mud and road spray build up quickly.

Driving with faulty lights is illegal even during daylight hours because poor weather or darker conditions can appear unexpectedly.

Lighting Legal Standards:

Checking your lights regularly only takes a few minutes and can help you avoid a fine or MOT failure.

5. Windscreen and Wipers

Your windscreen must provide a clear view of the road. Cracks and chips are only permitted within certain limits.

The legal limits are:

• No damage larger than 10mm in the driver’s direct line of sight
• No crack larger than 40mm elsewhere on the windscreen
• No stickers or objects that block your view

Windscreen wipers must also:

• Clear the screen effectively
• Operate without leaving smears or streaks
• Work with washer jets and washer fluid

Many drivers are surprised to learn that driving without washer fluid can also be an offence if it prevents the windscreen from being cleaned properly.

I remember speaking to a commuter from Birmingham who had ignored a small windscreen chip for months. When the crack spread across the screen, the driver admitted:

“I kept putting it off because it looked tiny, but after one cold morning it suddenly spread right across my line of sight.”

A damaged windscreen or faulty wipers can quickly make your car illegal to drive, especially during poor weather.

6. Mirrors

The law requires most cars to have at least two usable mirrors, typically a driver’s side mirror and either an interior rear-view mirror or a passenger-side mirror.

Mirrors must be in proper condition at all times. This means they should be:

• Securely attached
• Free from cracks
• Properly adjusted and unobstructed

Any damage or obstruction can reduce visibility and increase the risk of accidents, especially when changing lanes or reversing. Temporary fixes, such as tape or glued mirror pieces, do not meet legal standards.

Drivers of larger vehicles or vans may require additional mirrors to meet visibility rules. Keeping mirrors clean and correctly adjusted helps ensure a clear view of the road at all times.

7. Steering and Suspension

The steering system must allow you to control the vehicle accurately. If there is excessive play in the steering wheel, stiffness, or unusual noises, there may be a fault.

Suspension is equally important because it keeps the tyres in contact with the road. Worn shock absorbers, damaged springs, or uneven ride height can affect handling and braking.

Common signs of steering or suspension problems include:

• The car pulling to one side
• Knocking or clunking sounds
• Uneven tyre wear
• Excessive bouncing over bumps
• A steering wheel that feels loose or stiff
• A vehicle that leans to one side

I once heard from a driver in Leeds who said their car started leaning slightly after hitting a pothole.

The driver later explained:

“I thought it was just the road surface, but when the garage checked it, they found a damaged suspension spring that could have snapped completely.”

Steering and Suspension Faults:

If your steering or suspension does not feel normal, it is best to have the vehicle inspected immediately.

8. Exhaust and Emissions

The exhaust system must be in good condition and must not leak or produce excessive smoke. It also needs to meet legal limits for both noise and emissions to ensure the vehicle remains roadworthy.

To stay compliant, the exhaust should be securely attached, free from leaks or holes, and not produce excessive smoke. It must also operate within legal noise limits and include essential components like a catalytic converter or diesel particulate filter (DPF), where required.

Removing or tampering with these components can lead to an MOT failure and possible penalties.

Smoke colour can also indicate underlying issues:

• Black smoke: Too much fuel is being burned
• Blue smoke: Oil burning inside the engine
• White smoke: Possible coolant leak

Excessive or unusual smoke is often treated as a clear sign that the vehicle may not be roadworthy and requires immediate attention.

9. Number Plates

Number plates must be clean, clearly visible, and displayed in the correct format. The front plate must be white and the rear plate yellow.

Your number plates must:

• Use the correct font and spacing
• Be made from reflective material
• Be easy to read from a distance
• Be free from dirt, cracks, or damage
• Not be covered with tinted plastic or decorative covers

You can be fined if your number plate:

• Is dirty or difficult to read
• Uses an illegal font or spacing
• Has cracks or damage
• Is covered by a tinted plate cover

I once met a driver in Yorkshire who had fitted a stylised number plate because they thought it looked better.

After being stopped by police, the driver said:

“I only changed the lettering slightly because I thought it looked smarter. I never imagined it could lead to a £1,000 fine.”

A number plate may seem like a small detail, but keeping it legal is essential if you want to avoid unnecessary penalties.

How Do the Legal Requirements Compare for Each Car Part?

Different parts of the car carry different legal obligations and penalties. Some faults may only result in an MOT failure, while others can lead to heavy fines, penalty points, or even a driving ban if the defect is considered dangerous.

Comparison of UK Legal Requirements for Car Parts:

Keeping these parts in good condition not only helps you avoid fines and MOT failures, but also ensures that your vehicle remains safe and legal to drive every day.

Conclusion

If you are asking what part of the car does the law require you to keep in good condition, the direct theory-test answer is seat belts.

However, the wider legal answer is much broader. In 2026, UK law requires you to maintain every essential safety-related part of your vehicle, including tyres, brakes, lights, mirrors, steering, and number plates.

Keeping your car roadworthy is not just about passing an MOT once a year. It is an ongoing responsibility every time you drive.

By carrying out regular checks and repairing faults quickly, you can avoid fines, protect your insurance, and keep yourself and others safe on the road.

Frequently Asked Questions

Is the correct answer seat belts or tyres?

Seat belts are the standard answer to the theory-test style question. However, tyres are also legally required to be in good condition and can result in much larger penalties if they are unsafe.

Can you still be fined if your car has a valid MOT certificate?

Yes. A valid MOT only proves that the car was roadworthy on the day of the test. If a defect develops afterwards, you can still be fined.

What is the legal minimum tyre tread depth in the UK?

The legal minimum tread depth is 1.6mm across the central three-quarters of the tyre.

Are faulty brake lights illegal during the day?

Yes. Brake lights must work at all times, regardless of the weather or time of day.

Can you drive with a cracked windscreen in the UK?

Only if the crack is small enough to remain within legal limits. Larger cracks can make the car illegal to drive and cause an MOT failure.

Who is legally responsible if you are driving someone else’s car?

The driver is legally responsible for ensuring the vehicle is safe and roadworthy, even if they do not own it.

How often should you check your car to make sure it stays legal?

You should carry out basic checks every week, more detailed checks every month, and a full inspection before any long journey.