Anyone who has experienced the child support system knows it is complicated, but when parents who owe money do not pay up, it can push families below the poverty line.

A report due to be released later on Monday has revealed that failure to pay child support is widespread, with parents using loopholes in the system to avoid paying in full — or at all.

This includes putting assets under different names or not lodging tax returns for years.

The Swinburne University report comes as government figures show it is mostly fathers who owe child support debt, making up $1.54 billion of the total $1.64 billion owed nationally.

Mothers, who head more than 80 per cent of single-parent households, owe just $59 million in child support, while the gender breakdown of the remaining $42 million is unknown.

And on top of that, the total debt owed to parents is much worse than what is being reported, because it does not include any information about the 54 per cent of parental payments privately arranged.

"Their experiences and concerns and problems are completely invisible," said Associate Professor Kay Cook, who is behind the Swinburne University report.

"We have no data on this, the Government has completely turned a blind eye to it."

Those in the know say the whole child support system is failing parents.

"We're going backwards, despite an increase in technology … we could do so much better," said Terese Edwards, the CEO of the Council of Single Mothers.

But what is life like for these parents, who are left with so little at the end of the week that they are having to make tough choices about the way they care for their kids?

'It's exhausting. It's emotional'

Isabelle*, from regional Queensland, has been dealing with the system for 12 years since she split from her husband.

She has three children with autism, but their father has not paid a cent of child support.

All up, he owes her almost $60,000.

"The children need to be fed, the children need to be educated, clothed, housed," she said.

"It's exhausting. It's been 12 years and you get very emotional. Because you look back over years and think I've done it, but gee he made my life as hard as possible."

Isabelle is on a carer's allowance and she also takes in clothes for ironing to earn an extra $150 a week.

But her kids go without and she lives frugally, including going through half-price catalogues.

"It can be done. It can be tough. The kids don't have any after-school curriculum, they don't play sport anymore, there's nothing extra for them, just the basics," she said.

Isabelle's ex-husband works as a subcontractor and claims to have no income.

She believes he puts his assets in his new partner's name to avoid payment.

But when Isabelle has complained about his income or assets, she has been asked to complete a 'change of assessment' process, which means she has to hand over all of her personal financial information to the Government. He can then access it.

"Every little tiny bill … he gets to see them. He's supposed to see the same and I get to see his financials. He doesn't do it. So I don't get to see his, but he gets to see mine. It's an invasion of privacy," she said.

One of the Government's methods of encouraging repayment of child support debt is by enforcing overseas travel bans, called a Departure Prohibition Order.

Her ex is a dual citizen of another country and used to travel overseas frequently, but now cannot travel unless his debt is paid.

Here's what the report is calling for: Decoupling of child support payments from family benefits

Decoupling of child support payments from family benefits The Government to force all parties to lodge annual tax returns

The Government to force all parties to lodge annual tax returns No recalculation of child support payments on income estimates without proof

"He now just holidays [interstate]," Isabelle said.

"He has brand new phones. He has the latest dual-cab Toyota. They just bought a $600,000 property. His life hasn't altered. His life isn't hard."

"It's had no effect on him paying back any of this debt. But it does keep him in the country."

Ms Edwards said mothers were often also further disadvantaged because of the way child support interacts with family benefits, particularly Family Tax Benefit A, which is often calculated using expected child support income, rather than that which is received.

"What we're finding at the moment is there are over 200,000 child support customers who have not lodged a tax return for more than two years," she said.

"We find it's the first step of minimising and avoiding [payments]."

'He started playing games. I was beside myself'

Jess's* ex-husband was earning almost $900,000 as a partner in a firm when the marriage broke down in 2014.

"I went into our study and opened up our drawer of financials and everything, all our financials were gone. And it frightened me," Jess said.

"I opened up the internet banking and saw all our money was gone as well."

The split was acrimonious and took 12 months to go through the Family Court, racking up tens of thousands in legal bills.

Things became even messier when the child support agreement was formalised.

"He started playing games where he wouldn't pay on time and then he would delay his payments even further," she said.

"I had no money. I was beside myself."

Despite being in a similar role as he is now, in the last financial year he claimed his income had been slashed to just $129,000.

It means the child support he used to pay to help with their daughter has been drastically reduced.

Jess lives on a $50,000 disability pension provided through her super, but the change in his estimated income means she has been slapped with a $2,600 debt to pay to him.

"He's continuing to make me struggle by lowering his taxable income so his child support is lowered and therefore I owe him money. That to me isn't fair," she said.

She has complained to the Department of Human Services, but without success. She says she does not have enough money to take it to a lawyer.

"I'm not dumb, but I'm not an accountant. I can't seem to make heads or tails how they work out who gets what. I've stopped asking the CSA [child support agency], stopped complaining because it gets me nowhere," she said.

A spokesperson for the Department of Social Services says the Government "recognises the challenges faced by families who are experiencing relationship breakdowns, particularly when children are involved".

"The Government encourages any parent engaged in the child support system to utilise the agency collect service if they believe that their private collect arrangement is not suitable for their situation," the spokesperson added.

"During 2018-19, Services Australia facilitated the transfer of $1.6 billion in child support payments for more than 500,000 children through agency collect. Almost 95 per cent of all the agency collect child support liabilities raised since inception of the child support scheme have been collected."

This article contains general information only. It should not be relied on as financial advice.

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*Names have been changed for privacy reasons.