The rate of income tax applied to the next dollar of income earned, determined by which Stage 3 tax bracket the taxpayer falls into.
Stage 3 brackets (legislated): 16% to 30 Jun 2026, 15% from 1 Jul 2026, 14% from 1 Jul 2027. Higher brackets at 30%, 37% and 45%, plus 2% Medicare. The marginal rate determines how much tax saving a negative-geared property generates (under current law) and how much CGT applies on a sale.