Effective Tax Rate
The effective tax rate (also called the average tax rate) is your total income tax divided by your gross income, expressed as a percentage. It gives you a more realistic picture of your overall tax burden than looking at your marginal rate alone.
In New Zealand's progressive tax system, the effective rate is always lower than the marginal rate because your lower-bracket income is taxed at lower rates. For example, on a $70,000 salary the effective income tax rate is approximately 18.9%, even though the marginal rate is 30%. On a $100,000 salary the effective rate is about 22.9%, despite a 33% marginal rate.
When comparing tax across countries or evaluating a pay rise, the effective rate is more useful than the marginal rate. Keep in mind that the effective rate typically refers to income tax only — your total deduction rate is higher once you include ACC levy, KiwiSaver, and any student loan repayments.
How it works
Your effective tax rate is always lower than your marginal rate under a progressive system, because only the portion of your income inside each bracket is taxed at that bracket's rate — the lower brackets keep pulling your average down even as your top bracket rises. This is why two people with very different marginal rates can still have effective rates that are much closer together than the bracket labels suggest.
The effective rate is the more realistic number to use when comparing your overall tax burden year to year, comparing roughly how New Zealand's system compares with another country's, or judging the real impact of a pay change on your annual tax bill — it tells you what share of your total income actually goes to tax, rather than what happens to the next dollar you earn.
One caveat worth remembering: the effective tax rate usually refers to income tax alone. Your total deduction rate on a payslip will be higher once you add in the ACC earner's levy, any KiwiSaver contributions, and student loan repayments, none of which are counted as income tax.
Example: effective vs marginal rate on a $40,000 salary
On $40,000 for 2026-27, tax is 10.5% on the first $15,600 ($1,638) plus 17.5% on the remaining $24,400 ($4,270), totalling $5,908.
That's an effective tax rate of $5,908 ÷ $40,000 = 14.77% — noticeably below the 17.5% marginal rate that applies to the top slice of that income.
Frequently asked questions
Why is my effective tax rate lower than my tax bracket percentage?
Because only the income within each bracket is taxed at that bracket's rate — your lower-bracket income keeps being taxed at lower rates even after you move into a higher bracket, pulling your average down.
Does effective tax rate include ACC levy or KiwiSaver deductions?
No — effective tax rate usually refers to income tax only; your total deduction rate on a payslip is higher once ACC levy, KiwiSaver, and any student loan repayments are added.
Why does effective tax rate matter more than marginal rate for budgeting?
Because it reflects the actual share of your total income that goes to tax, giving a more realistic picture of your overall tax burden than the rate applied only to your last dollar.
Related Terms
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