Inflation Calculator — NZ CPI & Bracket Creep
Adjust historical dollar amounts for inflation using Stats NZ CPI, check whether your pay rise beat inflation, and see how unindexed NZ income-tax thresholds quietly push your real tax rate higher over time.
How much is a past dollar amount worth in today's money? Uses Stats NZ Consumers Price Index (CPI) annual averages.
$10,000 in 2000 is equivalent to
$18,454
in 2024 dollars
Cumulative inflation
84.5%
Annualised rate
2.59%
Years
24
Why NZ tax brackets and inflation matter together
New Zealand does not automatically adjust its income-tax thresholds for inflation. From 1 October 2010 until 31 July 2024 — almost fourteen years — the thresholds were frozen. Over that period, CPI rose by roughly 42% (from ~952 to ~1349 on the June 2006 = 1000 base). Even workers whose salaries only tracked inflation found a larger share of their income in the 30%, 33% and 39% brackets by the end of that period.
The Budget 2024 changes, effective 31 July 2024, lifted the three lower thresholds for the first time in 14 years. The 10.5% top rose from $14,000 to $15,600; the 17.5% top from $48,000 to $53,500; the 30% top from $70,000 to $78,100. The 33% and 39% thresholds ($180,000) remain unchanged. Because the change took effect mid tax year, the 2024-25 year uses composite thresholds that blend the old and new amounts.
This calculator lets you stress-test that policy: pick a current income, a CPI rate, and a number of years, and see how your effective tax rate drifts if the 2025-26 thresholds are held flat in the same way.
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Frequently asked questions
What CPI data does this calculator use?
Annual-average values of the Stats NZ Consumers Price Index (CPI), 1990 through 2024, with base June 2006 quarter = 1000. For example, the 2024 annual average is approximately 1349, vs 602 in 1990 and 952 in 2010. CPI measures the average price change of a fixed basket of consumer goods and services and is the standard measure of New Zealand inflation.
How is purchasing power calculated?
We multiply your historical amount by the ratio of the target-year CPI to the source-year CPI. So $1,000 in 2000 scaled to 2024 is $1,000 × (CPI 2024 / CPI 2000) = $1,000 × (1349 / 731) ≈ $1,845. Annualised inflation is the geometric mean of that growth over the number of years.
What is bracket creep and why does it matter in NZ?
Bracket creep (or 'fiscal drag') is when inflation pushes nominal incomes into higher tax brackets even though real purchasing power hasn't changed. NZ tax thresholds are not automatically indexed to inflation — they held flat from 1 October 2010 until 31 July 2024 — so CPI-only pay rises steadily raised workers' effective tax rates for 14 years. The Budget 2024 change was a one-off lift, not a formal indexation policy.
What changed on 31 July 2024?
Budget 2024 lifted the three lower thresholds for the first time since 2010: the 10.5% band top rose from $14,000 to $15,600, the 17.5% top from $48,000 to $53,500, and the 30% top from $70,000 to $78,100. The 33% and 39% thresholds ($180,000) were unchanged. Because the change took effect mid tax year, the 2024-25 year uses blended 'composite' thresholds.
Does the bracket-creep projection predict real inflation?
No. It assumes you get a CPI-matched pay rise each year at the rate you pick, holds the current 2025-26 thresholds constant (no future indexation), and shows what would happen to your real-terms tax burden. It's a what-if: if CPI runs at 2.5% for 10 years and brackets don't move, how much more tax do you pay in today's dollars?
How accurate are these numbers?
Purchasing-power and salary-erosion figures use Stats NZ's official annual-average CPI. Bracket creep uses the published NZ income-tax brackets from src/data/nzTaxData.ts. Neither includes ACC, KiwiSaver, student loan, or working-for-families effects — use the respective dedicated calculators for a full take-home view.
Why is my nominal raise positive but real raise negative?
Because inflation over the same period exceeded your raise. If CPI rose 15% between 2021 and 2024 and you received a 10% pay rise, your purchasing power fell by about 4.3% — a real pay cut despite a nominal increase.
Sources
CPI figures are annual averages sourced from Stats NZ (June 2006 = 1000 base) and rounded to whole index points. Bracket-creep projections assume the current 2025-26 thresholds are held flat for the projection window — this is a modelling assumption, not a forecast of government policy. Last updated April 2026.