What are the headlight rules in the UK?

Wednesday 8th October 2025

Whether you're a new driver getting to grips with your headlights or just want to make sure your lights are MOT-ready, this guide has you covered. We’ll explain when and how to use your lights at night and in poor visibility, as well as the condition they need to be in to comply with UK laws. 

When should you use your headlights and fog lights? 

Your vehicle is equipped with dipped (or low beam) headlights, full beams, and fog lights, each with specific rules for use. The Highway Code states your lights must not dazzle other drivers, but you must use them to ensure you're visible. 

In many modern cars, dipped headlights may turn on automatically. However, it's important to know when to switch them on manually, as sensors may not always detect the driving conditions accurately. In most vehicles, the headlight controls are located near the indicator stalk. 

When to use dipped or low beam headlights 

Dipped headlights should be used throughout the year in the following situations: 

1. At dusk, dawn and night: It might seem obvious to use your low beams at night, but it really is essential. Don’t forget to use them at dawn and dusk too for visibility; this is usually 30 minutes before it gets dark and the first 30 minutes of the day. 
2. During overcast days: Especially in autumn and winter when daylight is limited, switch on your dipped headlights in overcast or gloomy conditions. 
3. In rain, sleet, snow or fog: Dipped headlights not only help you to see in adverse weather conditions, but also allow you to be seen by other drivers and road users.  
4. Following other vehicles in low light: Always opt for low beam when you are driving behind someone to prevent your lights from shining into their rear-view mirror. 
5. Country lanes: Even during the day, using dipped headlights on narrow or winding roads helps other drivers see you coming around bends. 

How to use full beam headlights 

Using full beams correctly is essential for safe and considerate driving. 

When to use full beams 

• On unlit roads at night: Full beams help you see further ahead, making it easier to spot hazards like animals or pedestrians. 

• When there’s no traffic: Only use full beams when there are no oncoming vehicles or cars directly in front of you to avoid dazzling other drivers.

When to avoid using full beams 

• When there is oncoming traffic: Full beams can temporarily blind other drivers, creating a serious hazard. 

• When following another vehicle: The light can reflect off their mirrors and impair their vision. 

• In wet weather: Rain, snow, or wet roads can reflect the light, reducing visibility and increasing glare for everyone.

When to use fog lights 

Fog lights should only ever be used in specific conditions such as fog, heavy rain or snow. If you can see the rear lights of the car in front of you, you don’t need to switch your fog lights on. You have both front and rear fog lights: 

• Front fog lights help you to see in poor weather conditions when you would otherwise only be able to see 100 metres or less in front of you. 

• Rear fog lights should only be used when drivers behind you might not see your tail and brake lights in thick fog or poor weather conditions. If you use them when they aren’t needed, they could dazzle drivers behind you and make your brake lights harder to notice. 

Are LED headlights legal? 

LED headlights have faced a lot of criticism for being overly bright and potentially dazzling. However, if your vehicle came with LED headlights fitted by the manufacturer, they are legal. 

Replacement bulbs must be properly certified and type approved. Swapping a halogen bulb for an aftermarket LED bulb can increase glare and may not be road legal, so it’s best to stick to the same type of bulb if you need a replacement. Using the wrong type of bulb could result in a fine of up to £1,000, and you risk failing your MOT.  

Headlight requirements for road-legal use 

Did you know headlight issues are one of the most common reasons for MOT failures in the UK? With 1 in 5 vehicles failing their MOT for this reason. Follow these five headlight rules to keep your vehicle roadworthy and compliant with the UK headlight rules. 

1. Make sure both sets of lights work properly; both your dipped beams and main beams should be operational without flickering.  
2. Beam aim and pattern must be compliant. The aim of your beams should be downwards and slightly left of centre, away from oncoming traffic. Misaligned beams can cause an instant MOT fail. 
3. Headlights should be in good condition without significant misting and cracks.  
4. Headlights should be the correct colour and brightness; they should be equal and emit a white or yellow light.  
5. You must be able to switch between full beams and dipped beams easily. 

Make sure your vehicle is ready by following our guide on how to clean your head lights.  

Are your headlights ready and roadworthy for your MOT? Book your MOT now in just a few quick clicks.