Les McLean, from Woodham, Co Durham, had been paying pounds 120 a month to his former wife for the upkeep of their three children in the latest court order after the couple divorced in 1986. But after the Child Support Agency was set up in April, she had the court order revoked and asked for a new assessment by the agency, which raised the payments to pounds 480 a month.
When the Child Support Agency was set up, ministers said the main intention was to force absent fathers who did not pay any child maintenance to contribute.
Since the divorce, Mr McLean has set up home in Woodham with Lesley Livadas, a divorcee. They have a daughter, Bethany, 10 months, and a boy, Nicholas, 10 from Ms Livadas's previous marriage.
Mr McLean's former wife Christine is now married to Colin Bewley, a British Telecom engineer, and they live in Newton Aycliffe, Co Durham, with their two-year-old daughter and the three children from Mrs Bewley's first marriage - twin boys aged 15 and a daughter aged 19.
In April, Mrs Bewley went to court, had the pounds 120 maintenance payment order revoked and invoked the new Child Support Act. Under the Act, Mr McLean was judged not to be contributing any maintenance and the Child Support Agency ruled he must pay pounds 480 a month.
Mr McLean, who earns more than pounds 20,000 a year as a hospital manager, is incensed and has become the first father in Britain to take the matter to a county court. In a hearing later this month, he intends to appeal against the judge's decision to revoke the original maintenance payment of pounds 120 a month.
'The CSA was set up to ensure fathers paid for the upkeep of their children and I am all in favour of that,' Mr McLean said.
'But the law is being abused. Instead of low-income mothers getting help, the Act has resulted in fathers like me being clobbered despite the fact my former wife has remarried and is financially all right.
'It also doesn't seem to matter that I am in a new relationship with a mortgage and two children to support. My partner's ex-husband is in Greece and contributes nothing but that isn't taken into account.' He added: 'If my ex- wife had been unable to cope I would have been prepared to pay a little more but to put it up fourfold is ridiculous.'
Mr McLean said he was finding it difficult to survive under the new system. 'Before, I paid the pounds 120 every month but also regularly gave the children money towards holidays, for birthdays and pocket money and so on. Now one-third of my income is going to my ex-wife, I've had to tell the children I simply cannot afford to give them treats, we are having to scrimp and save just to survive.
'My court action is not intended simply to get at my ex-wife. It is to try and expose this loophole which is hammering caring fathers.'
Mrs Bewley, 36, said: 'This is a matter for the courts to decide and I do not wish to make any comment.'
A spokeswoman for the Child Support Agency said: 'Maintenance figures were calculated differently since the introduction of the Child Support Act.'
She refused to comment on specific cases, but said: 'In the past, payments ordered by the courts have been inconsistent and unrealistically low. The Child Support Agency has never sought to hide the fact that maintenance levels will, in a number of cases, go up. But it ensures far more appropriate payments are made.'
She said anyone unhappy wth the readjusted payments was entitled to have the calculation reassessed. 'Undoubtedly there will be cases like this. But figures are based on what it realistically costs to bring up a child and this will quite often mean higher payments.
'We will have assessed relevant incomes and decided the new payment is fair.'