If you are asking, can you drive with a cracked windscreen in the UK, the answer depends on the size, location and severity of the damage. It is not automatically illegal to drive with a cracked windscreen. However, it becomes unlawful if the crack obstructs the driver’s view of the road or renders the vehicle dangerous under section 40A of the Road Traffic Act 1988. Damage within the driver’s direct line of sight can also result in an MOT failure under DVSA testing standards.
Rule of thumb: it is only lawful to drive with a cracked windscreen where the crack does not obstruct the driver’s view and does not render the vehicle dangerous.
A cracked windscreen is therefore not simply a cosmetic issue. It is a question of roadworthiness, legal compliance and potential criminal liability. Police have the power to stop vehicles they believe to be unsafe, and drivers can receive penalty points and a fine for using a vehicle in a dangerous condition. In more serious cases, particularly where an accident occurs, the consequences can escalate.
What this article is about
This guide explains when it is legal and illegal to drive with a cracked windscreen in the UK. It sets out the relevant statutory framework, including the Road Vehicles (Construction and Use) Regulations 1986 and section 40A of the Road Traffic Act 1988. It also explains MOT windscreen rules, penalty points, insurance implications and the legal difference between a crack and a chip. The focus throughout is on practical compliance and real-world enforcement.
Section A: When Is It Illegal to Drive With a Cracked Windscreen?
The legality of driving with a cracked windscreen turns on two core legal principles: obstruction of the driver’s view and whether the vehicle is in a dangerous condition. UK motoring law does not impose a blanket ban on cracked glass. Instead, it applies functional safety tests, assessed objectively in the real world, not by what a driver hopes is “good enough”.
1. Regulation 30 – Obstruction of the Driver’s View and Safety Glass
Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 governs the glass fitted to motor vehicles, including the requirement for prescribed glass to be safety glass and the requirement that it is maintained so that it does not obscure the driver’s vision while the vehicle is being driven.
For most drivers, the practical compliance point is straightforward: if a crack interferes with your ability to see the road clearly, the vehicle is not compliant. A hairline crack at the edge of the windscreen may not amount to an offence. By contrast, a crack running across the driver’s direct line of sight is far more likely to breach the regulation.
The test is practical rather than theoretical. If a reasonable driver’s forward view is materially affected, the vehicle is not compliant. Even if the crack is small, glare from sunlight or headlights can distort vision and increase risk. Where visibility is compromised, continuing to drive may amount to a construction and use offence.
2. Section 40A Road Traffic Act 1988 – Using a Vehicle in a Dangerous Condition
Section 40A of the Road Traffic Act 1988 creates the offence of using a motor vehicle in a dangerous condition. The statutory test is whether the condition of the vehicle involves a danger of injury to any person, including the driver, passengers or other road users. This is an objective test. It is not necessary for the danger to materialise and the prosecution does not need to prove that an accident occurred.
A cracked windscreen may fall within this offence if, viewed objectively, it creates a real safety risk. This can include cases where:
- the crack significantly impairs visibility, including through glare, distortion or refraction of light
- the damage is likely to spread while driving, increasing the risk of sudden obstruction
- the defect is sufficiently severe to weaken the windscreen and increase injury risk in foreseeable scenarios
In practice, police officers and, if prosecuted, the court will assess the size, position and severity of the crack, along with conditions at the time such as night driving, heavy rain, low sun and oncoming headlights. Where a crack is extensive, spreading or directly in the driver’s line of vision, it is more likely to be treated as rendering the vehicle dangerous.
3. Police Enforcement in Practice
Police officers have broad powers to stop vehicles under the Road Traffic Act 1988. If an officer considers a windscreen defect to be dangerous or to obstruct vision, they may issue a fixed penalty notice or report the driver for prosecution. In serious cases, they may take steps to prevent further use of the vehicle until it is made safe.
Enforcement decisions are fact-sensitive. A minor crack away from the driver’s viewing area may result in advice. A large crack impairing visibility may lead to a fixed penalty or prosecution. The practical reality is that if a crack is obvious enough to attract police attention, it is often already close to the legal threshold of non-compliance, particularly where it affects the driver’s line of sight.
Section Summary
It is not automatically illegal to drive with a cracked windscreen in the UK. However, it becomes unlawful if the crack obstructs the driver’s view or makes the vehicle dangerous under Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 or section 40A of the Road Traffic Act 1988. The legality depends on visibility, severity and risk, not simply the existence of damage.
Section B: MOT Rules & Windscreen Crack Limits
While the question “can you drive with a cracked windscreen?” is primarily a matter of roadworthiness under construction and use law, MOT standards provide practical guidance on when damage becomes unacceptable. The MOT test does not itself create criminal offences, but it reflects DVSA safety thresholds and is often treated as a strong indicator of roadworthiness. An MOT pass is not a legal safe harbour and an MOT fail does not automatically mean criminal liability, but MOT standards are highly relevant when assessing visibility and safety risk.
1. What Is Zone A on a Windscreen?
The DVSA MOT Inspection Manual applies specific windscreen assessment areas. The most important is Zone A, defined as a 290mm-wide section centred on the steering wheel directly in front of the driver. This is the critical field of vision area. Because it corresponds to the driver’s direct line of sight, defects in this zone are assessed more strictly.
Even relatively small chips or cracks in Zone A can distort the driver’s view, refract light and increase glare from sunlight or headlights. For compliance purposes, Zone A is the area where marginal defects are most likely to cross the line into an MOT failure and, depending on their effect, into an obstruction of vision or dangerous condition concern.
2. Crack and Chip Size Limits for MOT Failure
Under DVSA testing standards, a pass or fail will depend on the location and size of the damage within the area covered by the windscreen wipers (the swept area).
- Damage larger than 10mm within Zone A will result in an MOT failure.
- Damage larger than 40mm outside Zone A but within the swept area will also result in an MOT failure.
The swept area is the portion of the windscreen cleaned by the wipers. Damage outside the swept area is assessed differently and may not trigger an MOT failure unless it significantly affects the driver’s view. Even so, damage outside the swept area can still be relevant to roadworthiness if it creates glare, distraction or an objectively dangerous condition.
It is also important to understand that these thresholds apply to both chips and cracks. A long crack measuring more than 10mm within Zone A will fail, as will a chip exceeding that threshold. Outside Zone A, the more generous 40mm limit applies, but the practical impact on visibility still matters.
3. Can You Drive After an MOT Failure for Windscreen Damage?
If your vehicle fails its MOT due to windscreen damage, you cannot lawfully continue to use it on the road unless you are driving it to a pre-booked MOT test appointment or to or from a place of repair. Even then, that exemption does not apply if the vehicle is in a dangerous condition. If the defect is treated as a dangerous defect, the vehicle should not be driven until repaired.
This distinction is critical. An MOT failure does not itself create a criminal offence, but driving a vehicle in a dangerous condition remains an offence under section 40A of the Road Traffic Act 1988 regardless of MOT status. In practical terms, if your windscreen crack is serious enough to fail an MOT, you should treat it as a compliance issue requiring prompt repair or replacement.
Section Summary
MOT windscreen rules provide practical thresholds: damage over 10mm in Zone A or over 40mm outside Zone A within the swept area will result in failure. These thresholds do not define criminal liability, but they strongly indicate when damage is likely to obstruct vision or raise dangerous condition concerns. If the crack affects visibility or is objectively dangerous, driving may breach section 40A of the Road Traffic Act 1988 and/or Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986.
Section C: Penalties for Driving With a Cracked Windscreen
If a cracked windscreen crosses the legal threshold from cosmetic damage to road safety risk, enforcement can follow. The consequences depend on how the defect is categorised, whether it obstructs vision or renders the vehicle dangerous and whether it has contributed to further offending or a collision. The law treats windscreen defects as part of the wider framework governing vehicle condition and roadworthiness.
1. CU20 Endorsement Code and Fixed Penalties
Where a cracked windscreen obstructs vision or renders the vehicle unsafe, the matter is commonly dealt with as using a vehicle in a dangerous condition. The DVLA endorsement code applied following conviction or acceptance of a fixed penalty is CU20, which relates to using a vehicle with parts or accessories in a dangerous condition.
In straightforward cases, the offence may be dealt with by fixed penalty. The standard fixed penalty is typically:
- 3 penalty points
- a £100 fine
If the case proceeds to court, the fine is at the discretion of the court and is not subject to the old Level 3 statutory cap, which was removed. The court will take into account the seriousness of the defect, the driver’s means and any aggravating factors.
Penalty points remain on the driving record and may increase insurance premiums. For drivers who already have points on their licence, further endorsements increase the risk of reaching the totting-up threshold.
2. Prosecution Under Section 40A Road Traffic Act 1988
If the crack is extensive, clearly obstructs vision or is linked to a collision, prosecution may proceed under section 40A of the Road Traffic Act 1988 for using a vehicle in a dangerous condition. As explained earlier, the statutory test is whether the condition of the vehicle involved a danger of injury to any person. The test is objective and does not require proof that injury actually occurred.
This offence carries:
- 3 penalty points
- a fine determined by the court
In more serious cases, particularly where visibility was significantly impaired and contributed to an accident, the prosecution may consider additional charges depending on the facts. The cracked windscreen itself may not be the sole basis of liability, but it can form part of a broader dangerous driving or careless driving investigation if evidence supports it.
3. Insurance and Civil Liability Implications
Driving with a cracked windscreen can also have insurance consequences. If the defect renders the vehicle unroadworthy and contributes to an accident, an insurer may challenge a claim under the driver’s own policy or argue contributory negligence in civil proceedings.
However, under the statutory framework governing compulsory motor insurance, insurers remain liable to satisfy third-party claims even where policy terms have been breached. The greater risk for the driver is therefore likely to arise in relation to damage to their own vehicle or potential recovery action by the insurer.
From a compliance perspective, knowingly continuing to drive with a crack that materially affects visibility increases both criminal exposure and financial risk.
Section Summary
If a cracked windscreen obstructs vision or renders the vehicle dangerous, the usual outcome is 3 penalty points and a fine, often issued by fixed penalty with endorsement code CU20. More serious cases may be prosecuted under section 40A of the Road Traffic Act 1988. In addition to criminal penalties, drivers face potential insurance and civil liability consequences if the defect contributes to an accident.
Section D: Cracked vs Chipped Windscreens – Legal Difference
Drivers often ask not only can you drive with a cracked windscreen, but whether the same rules apply to a small chip. In legal terms, the distinction between a crack and a chip is not decisive. The law focuses on visibility and danger, not on the label given to the damage. That said, cracks are more likely than chips to interfere with vision or weaken the windscreen sufficiently to create a dangerous condition.
1. Can You Drive With a Small Chip on the Windscreen?
A small chip located outside the driver’s direct line of sight and below MOT size thresholds will not usually amount to a criminal offence. The key legal question remains whether the defect obscures the driver’s view under Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 or renders the vehicle dangerous under section 40A of the Road Traffic Act 1988.
If a chip sits within Zone A and exceeds 10mm, it will fail an MOT. Even below that threshold, glare, distortion or refraction of light may still impair vision in practice. The objective test is whether the chip materially affects the driver’s ability to see the road clearly and safely.
From a compliance perspective, any chip within the swept area should be assessed promptly. Waiting for it to deteriorate increases legal and financial risk.
2. When a Chip Develops Into a Crack
Chips rarely remain static. Changes in temperature, road vibration, further impact from debris and normal vehicle flex can cause a small chip to spread into a longer crack. Once a crack extends across the windscreen, the likelihood of breaching visibility rules increases significantly.
A longer crack is more prone to:
- distorting the driver’s forward view
- causing glare from sunlight or headlights
- spreading further while the vehicle is in motion
At that stage, the argument that the vehicle is in a dangerous condition becomes stronger, particularly if the crack crosses the driver’s line of sight. Ignoring a small chip can therefore allow a manageable defect to escalate into a prosecutable one.
3. Structural Integrity and Occupant Safety
Although the legal framework focuses on visibility and danger of injury, structural integrity is relevant to the section 40A analysis. Modern windscreens are laminated safety glass, designed to remain bonded together on impact. They also contribute to the structural rigidity of the vehicle cabin and support correct airbag deployment.
If a windscreen is significantly weakened by extensive cracking, the case for it being in a dangerous condition strengthens. The law does not require total shattering before it intervenes. The threshold is whether the condition involves a danger of injury, not whether catastrophic failure has already occurred.
Section Summary
A small chip is not automatically illegal, provided it does not obstruct the driver’s view or exceed MOT thresholds. However, chips can develop into cracks that impair visibility or weaken the windscreen. Once damage interferes with vision or creates an objective danger of injury, driving the vehicle may breach Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 or section 40A of the Road Traffic Act 1988.
FAQs: Can You Drive With a Cracked Windscreen?
Is it illegal to drive with a cracked windscreen in the UK?
It is not automatically illegal to drive with a cracked windscreen. However, it becomes unlawful if the crack obstructs the driver’s view or renders the vehicle dangerous under Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 or section 40A of the Road Traffic Act 1988. The test is objective and focuses on visibility and risk, not simply the presence of damage.
Can you drive with a crack outside the driver’s line of sight?
Yes, provided the crack does not interfere with visibility and does not make the vehicle dangerous. A crack outside the driver’s direct line of vision is less likely to breach legal standards. However, if it spreads, causes glare or significantly weakens the windscreen, enforcement action may still follow.
How big can a crack be before it fails an MOT?
Under DVSA MOT standards, damage larger than 10mm within Zone A, the 290mm-wide area directly in front of the driver, will fail. Damage larger than 40mm outside Zone A but within the swept area of the windscreen will also fail. These thresholds apply to both cracks and chips.
How many penalty points do you get for a cracked windscreen?
If dealt with as using a vehicle in a dangerous condition, the usual outcome is 3 penalty points. This is commonly issued by way of fixed penalty with a £100 fine and endorsement code CU20. If prosecuted in court, the fine is at the court’s discretion and may be higher.
Can police stop you for a cracked windscreen?
Yes. Police have the power to stop vehicles if they suspect a defect affecting safety. If a crack appears to obstruct vision or pose a danger of injury, the driver may receive a fixed penalty or be reported for prosecution under section 40A of the Road Traffic Act 1988.
Does a cracked windscreen invalidate insurance?
A cracked windscreen does not automatically invalidate insurance. However, if the defect renders the vehicle unroadworthy and contributes to an accident, an insurer may challenge a claim under the driver’s own policy or raise contributory negligence in civil proceedings. Insurers remain liable for third-party claims under compulsory motor insurance law.
Section Summary
Driving with a cracked windscreen is lawful only if the damage does not obstruct visibility and does not render the vehicle dangerous. Once those thresholds are crossed, penalty points, fines and insurance consequences may follow.
Conclusion
If you are asking, can you drive with a cracked windscreen, the legal answer is conditional. A crack does not automatically make driving unlawful. However, once the damage obstructs your view of the road or renders the vehicle objectively dangerous, you are likely to be in breach of Regulation 30 of the Road Vehicles (Construction and Use) Regulations 1986 or section 40A of the Road Traffic Act 1988.
MOT rules provide practical size thresholds, particularly the 10mm limit within Zone A and the 40mm limit outside that area within the swept zone. While these standards are used for testing rather than defining criminal liability, they are strong indicators of when windscreen damage becomes unacceptable. An MOT pass does not guarantee legality, and an MOT failure does not automatically mean prosecution, but serious defects require prompt attention.
The typical penalty for using a vehicle in a dangerous condition is 3 penalty points and a fine, often issued by fixed penalty. More serious cases, especially where visibility is materially impaired or an accident occurs, increase the risk of court proceedings and additional liability.
The compliance position is clear. If a crack affects your line of sight, is spreading, or raises doubts about safety, repair or replacement should not be delayed. Roadworthiness is judged by risk. Once the risk crosses the legal threshold, liability follows.
Glossary
| Term | Meaning |
|---|---|
| Regulation 30 | Provision within the Road Vehicles (Construction and Use) Regulations 1986 requiring prescribed safety glass and that it is maintained so as not to obscure the driver’s vision. |
| Section 40A RTA 1988 | Offence of using a motor vehicle in a dangerous condition where the condition involves a danger of injury. |
| Zone A | The 290mm-wide section of windscreen directly in front of the driver used for MOT assessment. |
| Swept Area | The portion of the windscreen cleaned by the windscreen wipers during normal operation. |
| CU20 | DVLA endorsement code applied for using a vehicle with parts or accessories in a dangerous condition. |
| Roadworthy | A vehicle that meets legal safety standards and does not pose a danger to road users. |
Useful Links
| Resource | Purpose |
|---|---|
| Road Traffic Act 1988 – Section 40A | Statutory offence of using a vehicle in a dangerous condition. |
| Road Vehicles (Construction and Use) Regulations 1986 – Regulation 30 | Legal requirements relating to vehicle glass and obstruction of vision. |
| DVSA MOT Inspection Manual | Official guidance on windscreen defect assessment and failure thresholds. |
| Highway Code | Guidance on maintaining clear visibility and safe vehicle use. |
Author
Gill Laing is a qualified Legal Researcher & Analyst with niche specialisms in Law, Tax, Human Resources, Immigration & Employment Law.
Gill is a Multiple Business Owner and the Managing Director of Prof Services - a Marketing Agency for the Professional Services Sector.
