Offset Mortgage NZ: How It Works, Which Banks Offer It and Whether It Suits You

An offset mortgage is one of the most powerful — and most underused — home loan structures available in New Zealand. Instead of paying interest on your full loan, you pay it only on the difference between what you owe and what you hold in linked accounts. Done well, it can shave years off your loan and save tens of thousands, without locking away a cent of your savings. This guide explains how offsets work here, which banks offer them, and how to decide if one suits you. It’s general information, not financial advice.

How an offset mortgage works

Offset vs revolving credit

	Offset mortgage	Revolving credit
Structure	Loan and savings stay separate; savings offset the balance mathematically	Essentially a large overdraft secured against your home — spending and saving happen in the loan account
Discipline	Clearer boundaries — harder to overspend	Needs real discipline; the balance can creep up
Availability	BNZ, Kiwibank, Westpac	All five major banks
Rate	Floating (usually higher than the best fixed)	Floating

Both apply your savings against your loan; the choice often comes down to behaviour. If you might treat a revolving-credit facility as a spending account, an offset’s structural separation is a genuine advantage.

The practical takeaway: treat your linked offset account as your main transaction account — have your salary paid in, keep your emergency fund there, and let every dollar work against your loan until it’s genuinely needed. Because interest is calculated daily, even short-term cash counts.

Which banks offer an offset

True offset mortgages are much less common in New Zealand than revolving credit, and only a few banks offer them.

So if an offset structure matters to you, your mainstream options are effectively BNZ, Kiwibank and Westpac. BNZ’s TotalMoney is the most feature-rich — its family-grouping feature lets parents link their savings to an adult child’s mortgage to cut the child’s interest, without transferring ownership of the funds. You can model BNZ’s savings with our BNZ home loan guide. One caveat worth stressing: product availability and terms change, and sources sometimes disagree on the edges, so confirm the current offering directly with each bank before you decide.

Modelling your savings

Before committing, run the numbers. An offset calculator lets you input your loan balance, your average linked-account balance (use a realistic daily average, not your peak), your floating rate and your remaining term. As an illustration: a $550,000 loan with $35,000 averaged across linked accounts, at a 7% floating rate, saves roughly $2,450 in year one — and maintained over the life of the loan could cut the total interest bill by well over $60,000 and two to three years off the term, without ever raising the required repayment. For the current rate environment, see our NZ interest rates guide; Sorted also has a free mortgage calculator.

Offset (floating) rates are typically higher than the best fixed rates — in mid-2026, floating has been meaningfully above fixed. So you need enough in linked accounts for the interest saving to beat the rate premium plus any fees. A useful rule of thumb: an offset tends to pay off once your average offset balance is around 30% of your loan (or, more simply, once you’re consistently holding $20,000 or more accessible) — but the maths is personal, so model your own numbers.

Offset vs revolving credit

Revolving credit is often presented as the alternative to an offset, and both apply your savings against your loan — but they work differently.

Is an offset right for you?

You’re likely a good candidate if you consistently hold $20,000 or more in accounts; you’re on (or comfortable with) a floating rate; you have irregular income (freelancers, business owners, commission earners) with a fluctuating balance; you value penalty-free access to your savings; you have family willing to link accounts; or you’re a higher earner, making the tax-free saving more valuable.

An offset may not suit you if you have modest savings and the rate premium would outweigh the saving; you strongly prefer the certainty of a fixed rate (offsets are floating, so repayments rise when the OCR does — see our interest rates guide on the current upward direction); you’re a first-home buyer with little beyond your deposit; or you simply want the lowest headline rate, which fixed usually offers. Many borrowers use a split-loan approach — fixing part for certainty and running part as a floating offset — for example fixing $400,000 and offsetting $150,000. A mortgage adviser can help find the right split.

Tips to maximise the benefit

Consolidate your emergency fund and other accessible savings into linked accounts; have your salary paid in (even if it leaves within a fortnight, the daily calculation rewards every day it sits there); use a credit card for day-to-day spending and pay it in full each month from your offset, keeping more cash in the offset for longer; review fees annually, since monthly account fees erode the benefit; and don’t neglect KiwiSaver — those funds can’t be linked to an offset, but keep contributing for the employer match and government contribution (see our KiwiSaver guide) and weigh whether extra voluntary contributions are better directed to your offset instead.

Fees and conditions to check

Offsets aren’t fee-free — before signing, ask about the monthly fee for each linked account type, any establishment or legal fee, which account types are eligible to link, the family-grouping rules (including what happens if a family member wants their account removed), and any restrictions on lump-sum repayments or refinancing. And remember these are floating-rate products: when the OCR rises, your rate rises too, so factor rate-rise scenarios into your budget. For the fuller mortgage picture, see our home loans guide.

Disclaimer: This article is general information about offset mortgages in New Zealand, not financial advice, and not a recommendation of any lender or product. Rates, fees, product availability and account-linking rules change and vary by lender — the details here reflect 2026 and should be confirmed directly with each bank before you act. Offsets are floating-rate products, so repayments can rise. Consider advice from a licensed mortgage adviser for your own situation. For the calculator see Sorted (sorted.org.nz).

Frequently asked questions

How does an offset mortgage save me money?

You’re charged interest only on your loan balance minus the money in your linked accounts. Because NZ doesn’t tax the interest you save (only interest earned), an offset gives a tax-free “return” equal to your mortgage rate — which beats a taxed savings account, especially for higher earners.

Which NZ banks offer an offset mortgage?

Mainly three: BNZ (TotalMoney), Kiwibank (Offset Home Loan) and Westpac (Choices Floating with Offset). ANZ and ASB don’t offer a traditional offset — they provide revolving credit instead. Availability changes, so confirm with each bank.

Is an offset better than a fixed-rate mortgage?

It depends on how much you hold in savings. Offset (floating) rates are usually higher than fixed, so you need enough offset balance for the saving to beat the rate premium — a rough guide is around 30% of your loan. Below that, a cheaper fixed rate may win.

What’s the difference between an offset and revolving credit?

An offset keeps your loan and savings accounts structurally separate (the savings offset the balance mathematically), while revolving credit is essentially a large overdraft where spending and saving happen in the loan account. Offset gives clearer boundaries; revolving credit needs more discipline. Both use floating rates.

Do I lose access to my savings in an offset?

No — the money stays fully accessible for spending and emergencies. You’re not making an extra repayment; you’re just reducing the balance interest is charged on. Your regular repayment stays the same, but more of it goes to principal.

Can family members link their accounts to my offset?

Yes, with some banks. BNZ’s TotalMoney allows up to 50 accounts including family members’, and Kiwibank’s Offset allows up to 8 including a spouse, parents or children (personal names only). Westpac allows some family linking with conditions. Each account holder keeps full access to their own money.