But his solicitor held out the prospect of mounting a new legal challenge which could reduce the assessments absent parents are ordered to pay.
Gary Crozier, 34, a joiner from Gretna Green in Scotland, and his former wife, Jacqueline, had agreed a settlement when they divorced in 1988 which was endorsed by a county court in 1989.
Under the 'consent order' he signed over his half share in the marital home in lieu of paying maintenance for their son, Karl, now aged nine. The judge then ordered him to pay Karl a token 5p a year in recognition of the settlement.
After the CSA was set up in April it contacted Mrs Crozier, who was on Income Support, and sent Mr Crozier a maintenance assessment form. He was warned he would be liable to pay pounds 29 a week. The agency's formula does not take into account clean-break settlements and staff insisted he must pay the assessment.
Mr Crozier applied to the High Court to have the previous divorce settlement overturned, so he could recover his half share of the house.
His former wife is planning to re-marry and the house in Carlisle has been sold and realised equity of pounds 20,000. Mr Crozier said he wanted to invest his pounds 10,000 and use the interest to provide maintenance payments for his son.
The judge said yesterday that even though Jacqueline Crozier had agreed that the property transfer was in lieu of maintenance, she objected to his application and said she should retain the share and invest it to pay maintenance for their son.
The case was complicated by the fact that in November, after Jacqueline Crozier stopped claiming Income Support, the Child Support Agency wrote to Mr Crozier saying it would not be assessing him after all. As the agency had not made a formal assessment of the amount he would have to pay, the previous court arrangement stood. So although he will not have to pay the increased amount at the moment, he could in future, and decided to continue fighting the principle in court.
If Mrs Crozier went back on to Income Support the agency would intervene again. And once a formal assessment has been made, Mr Crozier's maintenance would continue to be fixed by the agency.
In a reserved judgment in the High Court in London, Mrs Justice Booth dismissed his application to set aside the previous consent order, 'harsh though the result may be for him'. The judge accepted that the couple had intended the property transfer to be 'in full and final settlement'. The order specifically stated that the mother would have full responsibility for maintaining the child.
However, she ruled that there could be no clean-break settlement between the father and son.
Mr Crozier's solicitor, Susan Deas, said he was 'disappointed but not surprised' by the judgment.
Mr Crozier, who lives with a new partner with whom he has a two-year-old child, is considering an appeal.
Ms Deas said she believed that in cases where there had been a clean-break settlement it would be possible to appeal against the part of the maintenance which is paid as a 'caring element' for the parent with care, usually the mother.
The formula allows for pounds 44 caring allowance, when the parent with care is on Income Support - the Treasury then claws back the Income Support she receives. Ms Deas said she had a client 'waiting in the wings' to bring such a case.
David Holder, organiser of the Campaign for Fair Maintenance, hopes to pursue this possible legal challenge. He said the Crozier ruling 'was an absolute disaster'.
'People see it as opening the floodgates for thousands of women to keep the clean-break settlement and then go to the agency to extract more money. There are a lot of devastated people out there,' he said.