A Moneybren tool
NZ OFFSET MORTGAGE CALCULATOR
An offset mortgage points your savings at your home loan in New Zealand — you pay interest only on the difference. This shows the interest saved, the years shaved off, and what your savings are really earning.
Your loan and your offset money
$
% pa
Offsets in NZ run on floating rates — check your bank’s current floating rate.
yrs
$
Savings, emergency fund, everyday accounts — everything linked.
$
Regular savings that stay in the linked accounts.
Used to show what a term deposit would need to pay to match the offset.
The offset saves you
$0
Without the offset
With the offset
What you still owe
Year-by-year detail
| Year | Offset balance | Interest — no offset | Interest — with offset | Balance — no offset | Balance — with offset |
|---|
How it actually works in New Zealand. Your repayment stays the same, but interest is charged only on the loan minus your linked balances — so more of every payment kills principal, and the loan dies years early. Your offset money stays fully available; it just stops earning bank interest and starts cancelling mortgage interest instead — tax-free, because money you don’t pay isn’t income. Only a few banks offer offsets here — always shop around, and check the floating rate you’ll pay, because offsets run on floating rates which sit well above fixed specials. The offset usually wins for money you need to keep accessible (like an emergency fund); for money you can lock away, compare against fixing more of the loan.
How to use this calculator
Enter your loan, the floating rate, and how much sits in your linked accounts (plus anything you add monthly). The calculator runs the loan with and without the offset and shows the interest saved and the time shaved off.
Then look at the gold card: it converts the offset into an equivalent term deposit rate. That’s the number to remember next time you see a term deposit advertised.
This is a tool only, and none of the information it produces is financial advice. Its accuracy is not guaranteed. Always check your own figures and get advice from your own financial professionals before making decisions.