I am a part time teacher- I work 0.6 (3 days) and I am able to get some family tax benefit A, but earn over the threshold for B. Family tax benefit A is based on both mine and my Dh income though, so it is a combined total.

The best thing to do would be to work out how much you can earn to be eligible for FTB A & B, there are some calculators on the family assitance site, and then average out how many shifts that would be per financial year. For me if I work a relief day I get paid about $330 a day, if I wanted to say earn under $5000 dollars a year I know that I can't work anymore than 15 days per financial year.

The other day to do it would be to decide how many days you are willing to work- 1 day a week/ 1 day a fortnight etc, and work out how much that would be over the financial year and plug it into their calculator.