It's saved the Palmerston family money and helped Ms Goldie return to full-time work, but the senior public servant said the children benefited most from a move away from childcare centres.

"I feel like we were living in a rut, the kids would have to leave the house at 7.30am, then we'd pick the kids up at 6pm, and have to start the dinner, start homework and showers - everyone was so stressed out," she said.

The parent-of-four used various forms of paid childcare for their first three children - aged between 6 and 15 - but when Lawson, 4, joined the family other options were needed.

Not only did little Lawson have a heart condition, but the cost of putting four children into childcare in the earlier years would have left little over from Ms Goldie's earnings.

Ronja Bartel, 18, arrived in January, becoming the sixth au pair in three years to join the Goldie house. Ms Goldie said au pairs in total, including extra food and utilities expenses, cost about $22,000 a year, a saving of $12,300 from the childcare which would otherwise be needed for her three youngest children.

Ms Goldie said as not everyone had space or interest in having a new adult living with them, nannies should be the priority when it came to extending the childcare rebate.

"It's more urgent to have nannies supported," she said.