The CSA's function was twofold, encompassing calculation of how much child maintenance is due (based on current legislation and rules) and collection, enforcement and transferral of the payment from the non-resident parent to the person with care.

The CSA could not get involved, even upon request, in the following circumstances (except in cases where the parent with care claims Income Support or Jobseekers Allowance): A new method of child maintenance calculation came into effect on 3 March 2003.

While the CSA planned to move everyone to the same system in due course, in the interim different people with identical situations would pay different amounts, based solely on when the case was first assessed.

One father, whose monthly payments would have dropped from £250 to £150 under the new rules, decided to take the CSA to the European Court of Human Rights, claiming that this discrepancy amounted to discrimination under article 14 of the convention.

[11] Sir Archy Kirkwood, chairman of Work and Pensions Committee, described the situation as "a systemic, chronic failure of management right across the totality of the agency.

[13] In February 2006, Secretary of State for Work and Pensions John Hutton asked Sir David Henshaw to redesign the child support system[15] with three key areas of focus; how best to ensure parents take financial responsibility for their children when they are apart, the best arrangements for delivering this outcome cost effectively and the options for moving to new structures and policies, recognising the need to protect the level of service offered to the current 1.5 million parents with care.

Responsibility for staff and functions passed from CMEC back to the Department for Work and Pensions on 30 July 2012, becoming the 'Child Maintenance Group'.

No new applications are accepted by the Child Support Agency, and existing cases are being closed on a planned progression basis, which is intended to finish by 2017/18.