Four single mothers have told the government they are seeking a judicial review into unpaid child maintenance.
The women said they wanted to "challenge the persistent failure" of the Child Maintenance Service.
Latest figures show £354m is owed by absent parents, but less than 10% of that has been clawed back.
The Department for Work and Pensions (DWP), which runs the service, said anyone "abusing the system at this difficult time" could face prosecution.
The women, from Yorkshire, London, Surrey and the North West, said they were owed payments of between £2,000 and £8,000 dating back a number of years.
They have notified the DWP that they intend to seek a judicial review after they were left in "financial difficulty and, in some cases, in poverty".
They have told how they have to use food banks, take on credit card debt and rely on other people's generosity in order to keep their children clothed and fed.
One mother, who lives near Selby in North Yorkshire, said: "My children go without every single day because their father absolutely refuses to put his hand in his pocket and the Child Maintenance Service, despite having a huge raft of powers at its disposal, does nothing meaningful to force him to cough up.
"Birthday money sent to my boys by relatives is saved up and spent on necessities like school shoes, instead of them being able to have a little treat of their choosing.
"I go without so my children don't. I never go out, I never spend money on myself - I'd rather use the little we have so they can go on things like school trips. I don't want my boys to be stigmatised."
Gingerbread, a charity which works with single parent families, said it was supporting the women in their legal action.
According to the charity, the Child Maintenance Service has collected little over £30m through enforcement actions, which is less than 10% of what is owed to single parents across the UK.
Charity chief executive Victoria Benson said: "It is a child's legal right to be supported by both parents, and yet the service designed to protect this right is failing them.
"It simply cannot be right that a government service is responsible for leaving children of single parents in poverty."
According to Gingerbread, there are about 1.8 million single-parent households. and about 90% of single parents are women.
A spokesperson for the DWP said: "No-one will get away with giving false information to avoid paying what they owe and all decisions carry rights of appeal, so either parent can dispute a decision.
"Those found to be abusing the system at this difficult time will find themselves subject to the full extent of our enforcement powers - including prosecution through the courts."