The head of the Child Support Agency has resigned amid widespread criticism of the agency's work, the Work and Pensions Secretary has said.
Doug Smith: 'Seriously disappointed' by new IT system
Alan Johnson said Doug Smith felt he had reached a "natural breakpoint at which to hand over the reins".
But an influential committee of MPs attacked "chronic, systemic failures" of management across the agency.
A year after a £456m IT system was brought in, thousands of single parents are still not receiving payments.
Mr Smith denied the new system was a "failure", but he said he was "seriously disappointed" with its performance over the past 18 months.
CSA - KEY FACTS
478,000 applications for support have been made over the
past 18 months
Of these - only 61,000 absent parents have made any payments
Calculations have been completed in around 140,000 of the cases
Another 100,000 have been closed
Applicants are waiting an average of an estimated 15-22 weeks for their first payment
The CSA target for this is just six weeks
The IT system bought by the CSA cost £456 million
IT suppliers EDS are losing a £1m a month on their contract
There are plans to cut the agency's staff by 2,600 by April 2006
At prime minister's questions in the Commons, Tony Blair dismissed calls from Liberal Democrat leader Charles Kennedy for the CSA to be scrapped and its work carried out directly by the Inland Revenue.
"It is highly unlikely that transferring this to the Inland Revenue will cause anything other than consternation to recipients and the Inland Revenue alike," he said.
But the prime minister acknowledged the situation was "unacceptable" and said the computer problems that had plagued the CSA needed to be sorted out.
Tory leader Michael Howard said the agency had failed some 750,000 families who "deserved better".
Earlier, giving evidence to work and pensions select committee, Mr Johnson said he respected CSA staff for dealing with a "problematic and unstable" computer system but said he did not have any quick solutions.
He said he had not made his mind up yet about whether to "pull the plug" on the computer system, saying things had improved but not enough to rule the "nuclear option" out.
Last year less than a half of all applications could go through the system without problems, now it was more like 90%, he said.
Committee chairman Sir Archy Kirkwood said he had never served on a committee where the evidence against the agency's performances was so "unanimous".
He told MPs: "This is not just about computers. It is a systemic, chronic failure of management right across the totality of the agency."
The CSA's troubled history includes a failure to collect £0.75bn owed to some of the UK's poorest families and having to write off a further £1bn.
The new IT system, purchased from computer firm EDS, was supposed to improve performance, but only half of applications have been processed.
Doug Smith said the recovery plan EDS drew up to restore its computer system to order had missed its targets and there was no date for having all old cases on the new computer system.
But he said he was convinced that EDS would be able to put things right if given time.
He said he thought he had done a "good job" and had only expected to serve for around three to four years when he took it.
CSA insiders say the IT system does not allow some of the simplest of changes to be made without throwing up error messages which then lock the case.
The government is withholding payments of nearly £1million a month from EDS because of the difficulties.
Editor of Computer Weekly Tony Collins said the fact the department had been unclear about its specifications from the outset had made things worse.
Liberal Democrat work and pensions spokesman Steve Webb said EDS was getting millions of pounds for a computer "that's supposed to do some pretty simple sums."
But he added that the CSA was a "bit like a tyre that has been patched time and time again and at some point you say it is just not remediable".