New Zealand Calculator Methodology
How Taxliva versions, calculates and labels New Zealand 2026–27 results.
Four calculation states
exact_supported means the documented formula is complete for the entered scope. indicative identifies a planning estimate. missing_inputs asks for facts needed for accuracy. unsupported prevents an incomplete statutory model from appearing exact.
Annual tax and payroll are different
Annual income tax uses progressive brackets. PAYE follows the official pay-period formulas, tax codes, ACC coordination and truncation rules; annual tax is never simply divided by 52 and called exact PAYE.
Rounding and privacy
Decimal arithmetic is used and monetary components round or truncate at their documented stage. Calculations run in the browser and do not require an IRD number or account.
Supported scope
PAYE, standard/estimation/ratio provisional tax and PIE calculations are exact within their declared inputs. Working for Families and property tools remain indicative because eligibility, exclusions and deduction classifications require facts that only the user or IRD can confirm. AIM is not reproduced outside approved accounting software.