Fiona Hill, who is the sole foster carer of two teenage children, said government payments fell short of covering essential costs by $170 a fortnight per child, or $4420 a year.

Ms Hill, of Seddon, said additional expenses for the 13-year-old boy in her care left her out of pocket a further $3800 last year. ''I don't want to stop being a carer, but I can't afford to keep doing this,'' she said. ''Last year was expensive, but I was prepared to wear the cost. But this year it's shaping up to be exorbitant.''

Ms Hill said incidental costs that could be claimed often took months to be reimbursed and that last year she was owed between $500 and $1000 at any one time.

''I'm on a good income and it stuffs up my budget, so carers with less money are really struggling. The time and effort that goes into being a foster carer is huge - we're counsellors, teachers and parents. But it's the additional costs and time spent chasing DHS [Department of Human Services] and justifying small amounts of money that is insulting.''

Ms Hill said it was also getting harder to claim for costs incurred when providing emergency respite to children.

''These are kids that are lucky if they have underwear with them when they arrive.''