Exchange or completion by 31 March?

[HavenSprings]

Hi, as we know the stamp duty relief will end 31 March, but does this mean that, for people wanting to avoid paying more, one needs to complete by 31 March, or just exchange will be enough to secure the old threshold?

You have to complete by 31st March to avoid the increase.

Thank you! I'll just have to pray that the landlord is feeling merciful then...