But someone correct me if I'm wrong - it will also depend on when in the financial year you make the change???

Because one of the FTBs is done based on teh lower- income person's income, if you suddenly start earning within this tax year, you could nudge out of the zone, and if he's already earnt a whole heap, he won't qualify either...is that right...except when the new financial year starts you can reset your estimates and then it'll just go back to being nearly the same as now.

Always a hassle when your income changes near the end of the fin year.