Can you stop in a yellow box when turning right?

Yes, if you are turning right and the only thing stopping you is oncoming traffic, or other vehicles waiting to turn right. If your exit road is blocked, wait behind the line, even on a green light: you MUST NOT enter the box until your exit road or lane is clear.

You know the rule. Can you spot it on the road?

Try it in a free scene

You want to turn right at traffic lights with a yellow box junction. The lights are green, but traffic is queuing in the road you want to turn into.

Work out what is really stopping you

The right-turn exception is narrow, and it is easy to stretch it further than it goes. Before you enter the box, look past it into the road you want to turn into. Then ask what would keep you from finishing the turn.

Oncoming traffic, or vehicles waiting to turn right: you may enter the box and wait.
A queue in your exit road: wait behind the line until there is space.
Both at once: wait behind the line, because the queue is still in your way.

Why a green light does not settle it

Green tells you it is your turn at the lights. It says nothing about the space on the far side. Go into the box with your exit full and you are stuck there when the lights change, in the way of the crossing traffic.

DVSA’s example of ignoring a box junction covers entering it partly as well as fully when the exit is not clear. Creeping in with only the front of the car is no way round the rule.

Once you are waiting in the box

If you have gone in properly and are waiting for oncoming traffic, stay ready to finish the turn. Staying in the middle after the repeater light has turned red and the oncoming traffic has stopped blocks the junction completely. When the way is clear, go.

Signalled roundabouts are different. There you MUST NOT enter the box unless you can cross it completely without stopping, so the right-turn exception does not help you.

How we mark each mistake

Practice marks only: on a real test, the examiner decides. How faults work.

You blocked the box junction Serious fault
Your exit road was not clear, so you were stuck in the box when the lights changed. You MUST NOT enter the box until your exit road or lane is clear.

See if you would make them

What the Highway Code says

Rule 174: You MUST NOT enter the box until your exit road or lane is clear. However, you may enter the box and wait when you want to turn right, and are only stopped from doing so by oncoming traffic, or by other vehicles waiting to turn right.
Rule 176: Only go forward when the traffic lights are green if there is room for you to clear the junction safely or you are taking up a position to turn right.

MUST and MUST NOT are the law. Should is advice, which can still be used in evidence in court.

Where this fits on the test

Top 10 fail reason: not responding correctly to road markings. DVSA driving skills: Junctions.