"They're very reliant on the contribution from the father - in most instances. It can be very serious and very disruptive to the stability of the family when the money doesn't come."
Figures released under the Official Information Act show liable parents in debt totalled 129,572 at the end of November.
Ms St John said non-custodial parents receiving a benefit were not able to skip payments, as the money was automatically deducted. But she wanted the Government to guarantee payments from those parents in paid work who failed to meet their child support obligations - making officials responsible for chasing payments arrears.
Father and Child support worker Cliff Shepherd said the payments were hard for some fathers to manage.
"And it's the anomalies that really frustrate and anger them.
"For example, we will have mum being paid money out of dad's benefit from Winz, and yet dad may be looking after the kids five days a week. [Yet] there's no money coming out of mum's benefit to pay dad."
A report into the scheme conducted by the Auditor-General in 2010 found Inland Revenue was doing a good job collecting child support debt, however more needed to be done to prevent liable parents getting into arrears.
Figures previously released under the Official Information Act showed at least 10 New Zealand fathers owe $1.3 million or more each.
Meanwhile, Inland Revenue is unable to find thousands of parents who owe child support payments. Many are believed to be living overseas.
By the numbers:
$9,643,061 owed by Wairarapa parents
788 parents with overdue payments
0.4 per cent of total national debt
969 Wairarapa children currently receiving support
$2.58 billion owed nationally
