A father is taking the Child Support Agency (CSA) to the European Court of Human Rights over claims he pays more than he should to support his daughter.
Mr Cook claims he is paying over the odds
Mark Cook is one of the victims of a new computer system which the agency said it could not address until it is working properly.
Mr Cook, from Cupar, Fife, pays £250 a month in maintenance for his daughter.
Under new rules he would pay nearly £100 a month less, but he is angry that the agency will not re-assess him.
Absent parents who are liable for the support of their children are now asked to pay a straight 15% of their disposable income.
It is a far simpler formula and new cases have been assessed in this way since March last year.
At the moment, the agency is refusing to re-assess old cases.
The CSA said all absent parents would eventually be assessed in the same way, but not before the new computer system was finally working properly.
Mr Cook said: "We should all be paying the same and this is my argument.
"I should be paying for my child. But I should not be paying different fees. That's discrimination as far as I'm concerned."
Mr Cook's lawyer Cameron Fyfe believes the situation constitutes discrimination and is taking the case to the European Court of Human Rights in Strasbourg.
Mr Fyfe said: "It is under the human rights act that we are bringing this application. Article 14 says there must be no discrimination.
"Discrimination has been defined as a policy or a decision which has no rational foundation.
"If ever there was discrimination this is it."