Overtaking another vehicle on the left is not something most drivers do every day, but understanding when it’s allowed and when it isn’t is crucial for safe driving and staying on the right side of the law. In the UK — where we drive on the left — overtaking on the left may sound counterintuitive to some, but there are specific situations where it is permitted. Breaking these rules can result in penalties, collisions, or misunderstandings with other road users, so knowing when you may overtake on the left helps you drive confidently and responsibly.
The General Rule
In the UK, the basic rule when overtaking is:
You should normally overtake on the right.
That’s because:
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Traffic flows on the left side,
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Vehicles on the right are usually travelling faster,
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And overtaking on the right maintains consistency and visibility.
However, there are exceptions where overtaking on the left is permitted — and in some cases the safest option.
When Overtaking on the Left Is Allowed
Here are the most common, legal situations where overtaking on the left is permitted under UK law:
1. When the Vehicle in Front Is Signalling to Turn Right
If the vehicle ahead is signalling or clearly preparing to turn right, you may overtake on the left — as long as it’s safe to do so.
For example:
A car in the centre lane is waiting to turn right at a junction — you may pass it on your left if there’s space and it doesn’t put anyone at risk.
This situation is perhaps the most common legal overtaking on the left.
2. On a One-Way Street With Multiple Lanes
In multi-lane one-way streets, the left lanes might be moving faster than the right.
As long as all vehicles are travelling in the same direction and you are not exceeding speed limits, overtaking on the left is allowed.
3. In Slow-Moving Traffic
If vehicles ahead are in slow queues and the lane on the left moves quicker — such as in heavy congestion — overtaking on the left is generally acceptable, provided it’s safe. You cannot weave dangerously between lanes.
4. When Directed by Traffic Signs or Road Markings
Certain road layouts, bus lanes, or temporary diversions may allow or even require traffic to pass on the left. Always obey the signs and markings.
When Overtaking on the Left Is NOT Allowed
Overtaking on the left should not be done if:
You would have to cross a solid white line to do it.
It creates risk or forces another road user to slow or change direction.
You pass on the left at a junction with ambiguous vehicle intentions.
You overtake on the left at roundabouts unless indicated safe.
Basically, being lawful also means being predictable.
Common Scenarios Explained
Scenario 1: Traffic Queue on A Busy Dual Carriageway
You are in slow traffic. The left lane begins moving faster than the right.
Allowed: Yes, if traffic is moving and you stay within speed limits and ensure safety.
Not Allowed: If you change lanes abruptly or create a hazard.
Scenario 2: A Driver Ahead Indicates a Right Turn
You’re on a dual carriageway and the car ahead signals right.
Allowed: Yes — pass on the left if there’s room and it’s safe.
This reduces delays and minimises unnecessary lane changes.
Scenario 3: Approaching a Roundabout
You are in the inside lane and someone signals to leave — but there is confusion.
Not Allowed: Do not overtake on the left here unless the driver in front clearly indicates right and space is safe to do so.
Roundabouts require predictable, controlled movements — overtaking on the left here is risky unless absolutely clear.
Is Overtaking on the Left Always Safer?
Not necessarily.
Many collisions occur when drivers overtake without checking blind spots or signalling. Whether overtaking on the left or right, the same principles apply:
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Check mirrors
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Signal early
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Confirm blind spots
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Ensure space to re-merge safely
A manoeuvre should only be attempted if you’re confident it won’t surprise other drivers.
Penalties for Improper Overtaking
If you overtake on the left illegally — such as on a bend or where road markings prohibit it — you may be liable for:
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£100 fine
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3 penalty points
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Possible court summons for more serious offences
Enforcement focuses on unsafe driving, not just technical rule breaches.
Quick Summary: When You May Overtake on the Left
Vehicle in front signalling right → Allowed
Multi-lane one-way street → Allowed
Slow, safe traffic conditions → Usually allowed
At roundabouts/junctions with unclear space → Not allowed
Related: How Should You Use Anti-Lock Brakes When You Need to Stop in an Emergency?
Conclusion
Overtaking on the left in the UK isn’t always illegal, but it must be done safely and in the right context. The default position for overtaking is on the right, but common sense and clear rules allow you to pass on the left when the vehicle ahead is turning right, on multi-lane one-way roads, or in slow-moving traffic — provided everyone’s safety is preserved.
FAQs
Can I overtake on the left at a traffic light queue?
Yes — if it’s safe, you’re not crossing solid white lines, and you’re not exceeding speed limits.
Should I overtake on the left if I’m in a hurry?
No — speed should never motivate riskier overtaking.
Is it legal to overtake on the left on a motorway?
On motorways, overtaking on the left is generally discouraged, except in slow congestion where lanes move at different speeds and it’s safe to do so.
What if the vehicle ahead doesn’t signal but moves right to turn?
Be cautious — overtaking on the left without clear signals increases risk and confusion.