Taxpayers will pay an extra £18bn for several government IT projects where costs are out of control, a joint report by Computer Weekly and The Times has revealed.
The spiralling costs were laid bare in a study of eight of government's largest IT projects by The Times newspaper.
An IT contract for the tax credit system that was originally set at £2.9 billion is now expected to cost £8.5 billion, the study showed.
A project to link to MoD databases is already up to £7.1 billion and a Ministry of Justice project (Nomis) to link records for each offender is reported to be overrunning by £456 million.
Despite the fact that some projects are years behind schedule and other have been scaled back or scrapped, government is expected to spend £102bn on IT projects in the next five years.
The revelations come just a week after a Public Accounts Committee report said the £12.7bn National Programme for IT (NpfIT) is not yet providing value for money after nearly seven years.
The NpfIT,which aims to link 30,000 GPs to nearly 300 hospitals, was originally estimated at £2.3 billion.
The all-party committee said there have been few successful deployments of the scheme's two main hospital systems.
The delays are despite the programme's spending of £2.4bn by March 2007, about £700m of which went on the central costs of supporting the programme.
The committee found that if problems with the hospital systems cannot be resolved it may be necessary to "renegotiate or terminate the existing contracts with the Local Service Providers - BT and CSC.
Little clinical functionality has been deployed to date with the result that the expectations of clinical staff have not been met. This is despite the award of central contracts for the programme five years ago, the committee said.
Although the committee's report raises questions about the feasibility of the NPfIT, the government is likely to reject the main findings. A formal response by the government is expected within two months.
Times Online: Secret computer deals that are costing the taxpayer billions