Stamp duty will be abolished immediately for first-time buyers buying a home of up to £300,000, Chancellor Philip Hammond has said.
For properties costing up to £500,000, no stamp duty will be paid on the first £300,000.
Mr Hammond said this meant 95% of first-time buyers would see stamp duty cut, while 80% would pay none at all.
The change will apply in England and Northern Ireland, and in Wales up until the end of March, but not in Scotland.
Scotland has an independent system of land tax. Stamp duty will be devolved to Wales from March 2018.
In the rest of the UK stamp duty is paid on all residential properties worth more than £125,000. The duty is levied at a staggered rate above that threshold, starting at 2% but increasing in line with the value of the property being bought.