Stamp duty - when liable?!

[Soph88888]

Quick question, we are due to exchange in the next week or so, with a completion set for September.
Obviously eagerly anticipating a reduction in stamp duty when the chancellor speaks tomorrow..

Just wondering when we become liable for stamp duty, on exchange or completion? I know we pay on completion but if he makes the change with immediate effect after we exchange would we still need to pay?

We spoke to an estate agent yesterday and he said it was due in completion. I was worried it might slow us down, but if t comes in straight away it could be really good for those of us trying to sell now!

Fab that's what I was hoping... it could make the difference between us being able to refurbish or have to save for another 2 years .. feels like just money down the drain.. I'd so love if they put a freeze on it!!!

In Scotland so it might be different but normally when there are changes it depends on when the contract was concluded (equivalent to exchange?