
The original deadline was 31 March 2021, but the new announcment means that:
Until 30 June 2021, no stamp duty will be charged on a residential property bought for up to £500,000.
Until 30 September 2021, no stamp duty will be charged on a residential property bought for up to £250,000.
From 1 October 2021, the stamp duty rate returns to pre-Covid-19 thresholds.