Marginal Tax Rate
The rate of tax applied to each additional dollar of income — determined by the tax bracket your top dollar falls into.
Your marginal tax rate is the rate of tax you pay on the last (highest) dollar of your taxable income. It corresponds to the tax bracket your income falls into. For example, if your taxable income is $80,000 in 2026-27, your marginal rate is 30% — meaning any additional dollar earned would be taxed at 30 cents (plus 2 cents Medicare levy).
The marginal rate is crucial for financial planning decisions such as salary sacrifice, tax-deductible contributions, and investment choices. When you salary sacrifice $1,000 into super, you avoid tax at your marginal rate (e.g., 30%) and instead pay only 15% contributions tax inside super — a net saving of 15 cents per dollar. Similarly, a tax deduction worth $1,000 reduces your tax by $1,000 times your marginal rate.
Note that your marginal rate is different from your effective (average) tax rate. Your effective rate is your total tax divided by your total income — it is always lower than your marginal rate because of the progressive bracket structure. For someone on $80,000, the effective rate is about 20.2% (including Medicare levy), even though the marginal rate is 30%.
How it works
Your marginal tax rate is the rate charged on your last, highest, dollar of taxable income — in other words, whichever bracket your top dollar falls into. It's not the rate you pay on your whole income, just on the slice at the very top. Someone with a taxable income of $150,000 in 2026-27, for instance, has a marginal rate of 37%, because $150,000 sits within the $135,001–$190,000 bracket, even though most of their income below that band was taxed at lower rates.
The marginal rate is what actually matters for financial decisions: it tells you how much of an extra dollar of income you'd keep, or how much a dollar of deduction is worth to you. A deductible expense is worth more to a 37%-marginal taxpayer than to someone on 30%, because the deduction is applied against that top rate before the lower brackets underneath it are touched. This is why the same $1,000 donation or work expense produces a different tax saving for different people.
The main trap is confusing the marginal rate with the effective, or average, rate — the marginal rate only describes the tax on the next dollar, not the overall proportion of income paid in tax, which is always lower once the tax-free threshold and lower brackets are averaged in. People sometimes turn down a pay rise or extra shift out of a mistaken belief that crossing into a higher bracket means losing money overall; in a progressive system that's never true, since only the portion above the threshold is taxed at the higher rate.
Example: what a deduction is worth at the 37% marginal rate
Suppose your taxable income for 2026-27 is $150,000, putting your marginal rate at 37% (the $135,001–$190,000 bracket). Partway through the year, you incur a $2,000 deductible work expense — say, a piece of equipment required for your job.
Because the deduction comes off the top of your income, it reduces the amount taxed at your marginal 37% rate, saving you $2,000 times 37%, which is $740, in income tax. Someone with the same $2,000 expense but a taxable income of $100,000, with a marginal rate of 30%, would only save $600 from the identical expense — the value of a deduction rises and falls with the taxpayer's marginal rate, not the size of the expense alone.
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Tax Brackets
The income ranges that determine the rate of tax applied to each portion of your taxable income.
Effective Tax Rate
Your total tax as a percentage of your total income — the actual overall rate you pay after all brackets, offsets, and levies.
Income Tax
Tax levied by the federal government on your taxable income, calculated using progressive tax brackets.
Salary Sacrifice
An arrangement where you direct part of your pre-tax salary into super (or other benefits), reducing your taxable income.
Taxable Income
Your assessable income minus allowable deductions — the figure used to calculate your income tax.