Thousands of housing transactions could collapse early next year because of a lack of staff to deal with the paperwork. And if would-be buyers do not get their mortgage applications approved before March 31, they would have to find up to an extra £15,000 to buy a home.
Extra work is over-stretching estate agents, lenders and conveyancers.
Lenders could withdraw mortgage offers, threatening tens of thousands of sales.
Experts warned civil servants earlier this month that there is not enough manpower to get these transactions through before the stamp duty deadline passes.
In July the Government increased the nil rate band of residential stamp duty in England and Northern Ireland from £125,000 to £500,000 to boost house sales.
Tom Scarborough, chief executive of MoveWise.co.uk, said: “There’s a growing call for the stamp duty holiday deadline to be extended to avoid thousands of property transactions collapsing in February and March.
“Conveyancers are struggling to get through the backlog.”
Figures out yesterday showed house prices hit a high for the fourth consecutive month in November.
The average property is £229,721 after jumping by 6.5 percent annually.