Wairarapa parents owe $10.4 million in unpaid child support payments - of which $7.4 million is late payment penalties.
More than 1500 parents in the region have child support payments owing to IRD, which collects payments on behalf of parents, in the last financial year.
Parents who do not have full custody of their children are paying an average of $1382 per year, per child - around $26 a week - and made $2.8 million in child support payments between 2010/11.
IRD sets child support payments on a sliding scale depending on how many children a parent is liable for - 18 per cent of income for one child, and up to 30 per cent for four or more. The percentage is reduced if the parent shares care.
An IRD spokesperson said the child support contributions aimed to reflect the costs to parents of raising children and were based on international practice.
But some parents on both sides say the system is not fair.
One Masterton man who had a child with an on-off girlfriend eight months ago, has had to put his house on the market to keep up with the payments.
Builder Lindsay James is required to pay 18 per cent of his before-tax income, after a living allowance of $14,679 is deducted, which amounts to around $125 a week.
Mr James said his mortgage, groceries and bills left him with just $50 from his take-home pay and the child support payments would put him further into debt.
"I admit I've got a responsibility to pay money, I've got no problem with that, but I disagree with the scale because the cost of living for every person is different."
He says payments should be set on an individual's circumstances, including their other financial obligations.
Mr James is applying to have his payments reviewed, a formal process done in consultation with the other parent.
A Martinborough man, who did not want to be named, said after years wrangling with custody and child support issues he saw the system as the ambulance at the bottom of the cliff.
"The problem is way higher, in the process of separating families. Any changes in child support will not improve the situation - the improvements need to be made at the top of the cliff with improvements in how couples separate, and go on to raise children between them."
He said the child support system should be managed by Family Court judges. "A case should be presented and a decision made on the basis of the real situation rather than by formula.
"I would have paid more if I had any money, but the reality was that I didn't. It does not surprise me that there is such a huge sum of outstanding payments."
Carterton mum Liz Rikiti said she has had constant issues with child support payments for her 7-year-old. Ms Rikiti said her ex-partner had other children he paid child support for - which meant the payments got split between them, leaving her with $8 a week.
"It's just really, really frustrating. It's the little things, driving them around, the costs of school, and weekend hobbies - she's missing out on so much because of it."
Ms Rikiti said IRD should carry out regular reviews of a parent's circumstances to ensure children were getting what they should.
An IRD spokesperson said the Child Support Act put the onus on parents to advise them of a change in circumstances, but they reminded them regularly. Penalty payments are kept by the Government to offset administration of the scheme, and penalty write-offs are available for parents who make and comply with a repayment arrangement.
