Working less - and working more - means more WFF assistance

I was interested to see this story where Josephine Kent says that if she works less hours she gets more money in the hand thanks to Working for Families.

When she worked 51 hours a week, the net family income - after paying for childcare and tax - was $1029.67 a week. When the family had a high total income, it was not eligible for a childcare subsidy, which varies according to income.Now she works 23-30 hours a week. For 30 hours the net income rises to $1075.35, and for 23 hours it goes up to $1109.91.

Apparently it works the other way, too. Just the other day I had a friend who picked up a 16 hour a week job at $20.00 per hour after not working for a while. He has a partner and two children. His partner also works part time - but because the family now works 30 hours a week they are entitled to the In Work Payment - and he told me that the family gets more from Working for Families even though they are working 16 hours extra a week. That's because the decrease in family support is less than the amount they are getting from the In Work Payment.

Incredible - at least he thought it was.And they are probably entitled to abated childcare subsidies on top of that, but as both partners work at different times they don't need it.

I wonder what the best value income/WFF split is. In other words what is the maximum you can earn for the best value for WFF to get the best combined pay/WFF dollar rate?

Does anyone know?