Does a word used many times in an Act always have the same meaning? Not necessarily. The presumption that words are used consistently depends on context6. In this case (at ) the presumption was applied, consistent with the clear meaning of the text and its structure.
The presumption is given less weight in frequently amended Acts, and in those which have to deal with a range of different subjects and policy settings (like tax laws)7. In tax situations, however, many terms are also defined in the Act itself – see the dictionary in ITAA97, s 995-1, for example. iTip – don’t assume a word always has the same meaning, and remember to check if your term is defined somewhere in the Act (whether it has an * or not).
This case is from Episode 3 of interpretationNOW!
6 Murphy v Farmer  HCA 31 (at ) (meaning of ‘false’).
7 Pearce & Geddes (at [4.7]), Clyne  HCA 40 (at ).