The unexpected resignation of Ros Hepplewhite last week indicates the pressures at work. But her replacement as chief executive by Ann Chant can only be an aspect of the solution. Ms Hepplewhite must bear responsibility for the chaotic way the CSA dealt with some cases. But ministers are to blame for approving a formula for assessing child maintenance payments that is unfair and obscure.
These problems with the 1991 Child Support Act were identified at the time, but with no effective lobby behind the campaign, ministers chose to ignore them. In part, they were swept along by popular support for the principle of requiring fathers to take financial responsibility for their children. It is also true that the Act was a pioneering move in the UK - albeit drawing on overseas experience. Well implemented, such schemes help lone parents out of the poverty trap, while reducing public expenditure.
But the details enshrined in the British law are an offence to natural justice. Second families are often left with too little money because of claims for the children of a first family. Assessments take no account of property that may have been transferred when a couple split up; from 1996 even court settlements can be torn up. Those who feel hard done by have no right of appeal to an independent body.
These failings might be less glaring if lone mothers had materially benefited. But the poorest are no better off because most lose dependable income support pound for every pound that is demanded of an absent parent, whose payments may be unreliable.
Peter Lilley has tinkered with the formula to make it fairer. At a stroke, the Secretary of State for Social Security could do more. 'Clean-break' settlements should be taken into account when assessing an absent parent's liability. So should that person's expenses: the costs of loans, travel, gifts and of supporting stepchildren.
However, even these improvements will not tackle the fundamental faults in the CSA. To achieve a lasting solution, ministers should amend the legislation. First, a reformed law would distinguish between couples who have already separated and new break-ups. Less should be demanded of those who made their family arrangements according to the law as it then stood. Second, the formula for assessing maintenance should be simplified so that all parties have a better understanding of how settlements will affect them.
Ministers shrink from these measures because they would bring a controversial subject back to the centre of the political stage. This is a mistake. Without firm action now, they will be inviting some of their most natural supporters to approach a general election with a powerful sense of justice denied.