Government spending watchdog, the National Audit Office, estimates that by its 2020 target date only sufficient land to build 65,000 homes will have been released.
But it found that the Government had benefited from improved land values and was on track to raise its target of £5bn in proceeds by selling land and property.
The government now expects to reach it 160,000 homes goal five years later than hoped.
So far two transactions have been responsible for raising more than £1.8bn.
The largest single sale in the present 2016-2020 programme was the Old War Office, which the Ministry of Defence sold in 2016 for £357m.
Network Rail completed the sale of railway arches in February 2019, generating proceeds of £1.46bn.
This leaves the Government needing to generate a further £1.06bn worth of proceeds in the final two years of the programme.
The Ministry for Housing, Communities and Local Government identified several challenges to delivering the target. Sales of some large, complex sites have been delayed due to planning issues, while others required decontamination.
NAO’s analysis shows that of the 1,500 sites sold between April 2015 and March 2018, 176 (12%) were sold for £1 or less.
MHCLG said that the main reasons for the nominal sale prices were that buyers had to incur costs of remediation, other sites were narrow strips of land which had no other use, and other plots came with contractual conditions attached.
Most of the sales involved small properties but five transactions involved sales of sites bigger than 10 hectares.