**Threshold: $190,001 taxable income.**

The 45% rate applies to taxable income **over $190,000**:

\[
\$4,288 + \$27,000 + \$20,350 = \$51,638
\]

Thus, for taxable income above $190,000:

\[
\text{Income tax} = \$51,638 + 45\% \times (\text{taxable income} - \$190,000)
\]

The rates are set by the **Commonwealth Parliament** under the **Income Tax Rates Act 1986 (Cth)**. The Australian Taxation Office administers, but does not set, the rates.