Manurewa mother Katrina Hill can't win. One part of Paula Bennett's Social Development Ministry is telling her to go back to work, while another has told her to stay home with her children.

Hill's work ethic is surely more than anything Bennett could ask for. She has spent years in the security industry, working night shifts while her children slept.

For two years after her marriage broke up in 2006 she worked 72 hours a week to keep food on the family's table - only to be told by the Ministry's Child, Youth and Family Service (CYFS) to cut back.

"One social worker said I needed to be with the children. Another social worker praised me for being a working mum and asked, 'how do you do it?"' she says.

Hill has four children, now aged 17, 15, 12 and 9. Her husband first made her move out with the children, then took the children to live with him and his new partner in Australia in 2008. He sent them back to Hill when his new relationship broke up last year.

Unsurprisingly, her children have had problems.

"When I was working, I found my son was playing with lighters and hanging out with young kids who were smoking. If I had supervised him a bit more he wouldn't be doing that," she says. "The amount of times I've been called home to sort my children out, it's not worth the stress. I just recently had an incident where I grounded my 12-year-old daughter for her verbal behaviours. She ran away and called the police."

Hill cut back her hours as a noise control officer from 12 hours (6pm-6am) to six (10pm-4am), leaving her 17-year-old daughter Sam in charge.

"That was still unacceptable to CYFS because at Sam's age - she wants to go out."

Hill has now stopped work altogether. She is looking for daytime work for 20 hours a week "to keep my head above water" - but her children now come first.

Former Manukau truancy officer Therese Luxton told hearings on Bennett's Future Focus Bill that making sole parents go back to work after the children turned 6 would lead to more family stress.

When a similar law was introduced by the last National Government in 1999, an evaluation by the Ministry in 2001 found a quarter of the sole parents who went back to work were doing either shift work (14 per cent), evening or night work (9 per cent) or working on call (4 per cent).

Even after the law was relaxed in 2002, Luxton told MPs that Manukau truancy officers found at least five cases a term of children being left at home alone and many more left with siblings under 14.

"Children of single working parents regularly arrive late to school, leave early or are left with relatives, as it's an easier option than attending school," she said.

Luxton has been called out to help a 9-year-old girl with special needs found sitting on the street while her sole-parent mother was at work, and a 7-year-old boy she found hiding behind the woodpile at home when his working mother left him in the care of his 17-year-old brother.

"They thought he was at school, but I think he had missed school so much he was behind and felt like a failure," Luxton says.

She believes there are "huge benefits" from having a parent at home for a child's language development and mental health.

"I actually think the answer is that employers get some sort of tax break or incentive to employ solo mums and make allowances for the kids and everything else they have to go to," she says. "My [sail-making] brother-in-law in Nelson only employs mothers to work for him.

"The condition is that if their kids are sick, or they have to attend anything at school, he lets them go, no questions asked. In return, if he has a big order to fulfil, they will support him 100 per cent."