New Zealand Student Loan Repayment Calculator (2025/2026)

Mathematical Derivation & Variable Explanations: New Zealand tertiary student loans are administered by Inland Revenue (IRD) under the Student Loan Scheme Act 2011. For domestic tax residents who reside primarily in New Zealand, student loans carry an interest rate of exactly 0%, with compulsory repayments collected automatically through the employer Pay-As-You-Earn (PAYE) tax withholding system.

• The Statutory 12% Repayment Threshold Algorithm: You are legally required to make repayments only on income earned above the annual statutory repayment threshold:
  $$D_{\text{annual}} = 0.12 \times \max\left( Y_{\text{gross}} - T_{\text{threshold}}, \; 0 \right)$$
  For the 2024/2025 and 2025/2026 tax years, the annual statutory threshold is $24,128.00 ($464.00 per week, or $928.00 per fortnight). Every dollar of gross earnings above $24,128 incurs a mandatory 12.0% repayment deduction (tax code 'M SL').
• Amortization Timeline Closed-Form Equation: Because domestic New Zealand student loans accrue 0% nominal interest ($r = 0$), debt amortization is purely linear:
  $$\text{Years to Pay Off} = \frac{B_0}{0.12 \times (Y_{\text{gross}} - \$24,128) + V_{\text{voluntary}}}$$
  where $B_0$ is your outstanding loan balance, and $V_{\text{voluntary}}$ represents any optional direct payments made to Inland Revenue.
• Overseas Borrower Interest & Fixed Tier Repayments: If you leave New Zealand for more than 183 consecutive days, your loan becomes an overseas student loan. Under Section 106, your interest-free status is revoked, and the loan accrues interest at 3.9% p.a. (for 2024/2025). Furthermore, repayments cease to be income-contingent and are replaced by rigid statutory annual payment obligations based on loan balance:
  • Loan Balance $\le \$1,000$: Entire balance due in full.
  • Balance $\$1,001 - \$15,000$: $1,000 per year ($500 half-yearly).
  • Balance $\$15,001 - \$30,000$: $2,000 per year ($1,000 half-yearly).
  • Balance $\$30,001 - \$45,000$: $3,000 per year ($1,500 half-yearly).
  • Balance $\$45,001 - \$60,000$: $4,000 per year ($2,000 half-yearly).
  • Balance $> \$60,000$: $5,000 per year ($2,500 half-yearly).
• Mortgage Borrowing Capacity Impact (CCCFA Rules): Under the Credit Contracts and Consumer Finance Act 2003, retail banks treat the 12% student loan payroll deduction as a permanent, non-discretionary reduction in take-home pay, typically stripping $40,000 to $70,000 from your maximum home loan borrowing power.