A government spokesman admitted, "Until the system is in place, nobody knows what is happening with regard to the budget." He was unable to deny reports that the CSA's new computer system is £50m over budget and is likely to be delayed until next summer - more than a year after its original implementation date.
The Department for Work and Pensions, which is responsible for the CSA, said the system is undergoing "rigorous testing" from supplier EDS. It does not know when the system will be available or how much it will cost to deliver.
The CSA has been left to make do with its existing IT system, which has been severely criticised in the past. More than two years ago the House of Commons Public Accounts Committee warned that the CSA would have to rectify errors in its existing computers if new IT systems were to work.
The Westminster financial watchdog was horrified at the level of errors, with one in four assessments wrong, one in three payments from parents wrong, and four out of five maintenance balances incorrect.
The government spokesman said, "It is not perfect but there have been improvements under the old system."
The new IT system was meant to be up and running by the end of April this year, although Alistair Darling, the then secretary of state for work and pensions, told MPs in March that the system would be delayed while testing was carried out.
Describing the delay as "frustrating and regrettable", Darling promised MPs that his department would not pay for the new system until it meets the required standard. Five months on, there is still no indication of when the £200m system, which is being developed under the Private Finance Initiative, will go live.
Liberal Democrat IT spokesman Richard Allan called on the Government to explain who was at fault for the delay. "Responsibility for this delay lies with the officials who commissioned the project and who are overseeing its implementation," he said. "They must either make it clear that the contractors are at fault and what penalties will be paid or accept the responsibility themselves."
The new IT system, which is crucial to the Government's planned reforms of the CSA, will provide simple maintenance level calculations based on 15% of a parent's income for one child, 20% for two children and 25% for three children.
Derek Huxley, secretary of the Campaign for Justice in Divorce, which is lobbying for the reform of child support legislation, said, "The IT systems at the CSA have always been problematic."
A spokesman for EDS confirmed that the system is now complete and is undergoing testing.