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Split your loan between standard and offset or revolving credit, add extra payments, and see a full restructuring plan — with automatic rate adjustments as your LVR improves.
Most New Zealand borrowers put their entire loan on a single fixed rate and never think about it again. But splitting your mortgage between different account types — standard, offset and revolving credit — can save tens of thousands in interest and shave years off your loan. This guide explains how each strategy works and when to use it.
Mortgage splitting means dividing your home loan into two or more “tranches” — each with its own rate type, term or account structure. For example, you might put 70% of your loan on a low fixed rate for repayment certainty, and 30% on a revolving credit facility so everyday savings reduce your interest daily. New Zealand banks like ANZ, ASB, BNZ, Westpac and Kiwibank all allow split structures at no extra cost.
A single-rate mortgage is simple but inflexible. Splitting lets you lock in certainty where you need it, keep flexibility where it counts, and use your savings to offset interest — all at the same time. Even a modest split can save $10,000–$30,000 over a 25-year loan depending on how much cash you keep in offset or revolving accounts.
There are three main ways to structure a split mortgage in New Zealand. Each uses a different flexible account alongside your standard fixed or floating portion.
An offset account links your savings to your mortgage. If you owe $500,000 and have $60,000 in savings, you only pay interest on $440,000. Your savings stay accessible — you can withdraw at any time — but every dollar parked there reduces your daily interest charge.
A revolving credit facility works like a large overdraft secured against your home. Your salary goes in, reducing the balance, and you draw on it for daily expenses. The key is that interest is calculated on the daily closing balance — so even temporary deposits reduce your costs.
Advanced borrowers can combine all three: a large fixed portion for certainty, a smaller offset for liquid savings, and a revolving facility for everyday cash flow. This is the most flexible structure but requires more active management. Our optimizer models multi-split scenarios automatically.
The optimizer runs a month-by-month simulation of your mortgage over the full loan term. Here's what happens behind the scenes:
If you're new to mortgage splitting, start with 10–20% on revolving credit and the rest on a competitive fixed rate. As you get comfortable managing cash flow, you can increase the flexible portion at your next re-fix date — with no break fees to worry about.
Both offset and revolving credit reduce your interest by leveraging your cash, but they work differently and suit different borrowers.
Yes. Some borrowers use revolving credit for everyday cash flow (salary in, expenses out) and a separate offset account for longer-term savings like an emergency fund or investment deposit. This keeps your spending and savings separate while both reduce your mortgage interest.
Restructuring doesn't have to mean refinancing with a new bank. Most changes can be made with your existing lender at no cost if you time them correctly.
When your fixed term expires, you can renegotiate the split without any break fees. This is the ideal time to move a portion onto revolving credit or add an offset facility.
When your LVR drops below 80% (or 70%, or 60%), you qualify for lower rates. Ask your bank for a rate review — many won't offer it unless you ask.
Getting a pay rise, receiving an inheritance, or changing jobs are all good triggers to revisit your split. More income or a lump sum means more benefit from offset or revolving credit.
It depends on the size of your loan, the cash you keep in offset or revolving accounts, and current interest rates. As a rough guide, a borrower with a $600,000 loan keeping $40,000 in an offset account could save $25,000–$50,000 in interest over 25 years and pay off their mortgage 2–4 years sooner.
They're similar but not identical. In New Zealand, revolving credit (also called a “flexi” or “orbit” facility) is a portion of your home loan set up as an overdraft. It doesn't require a separate application like a home equity line — it's simply part of your existing mortgage structure.
Most NZ banks allow splits at no extra cost. Some charge a small annual fee ($30–$50) for a revolving credit facility or offset account. The interest savings almost always outweigh the fee — even with just $10,000 in the account.
Yes. At your re-fix date, you can adjust the split between standard, offset and revolving portions with your existing lender — no new application, no new valuation. Mid-term changes to a fixed portion may attract break fees, which is why the optimizer plans changes around your re-fix schedule.
An offset account benefits you regardless of the rate — lower rates just mean a smaller absolute saving per dollar offset. If rates drop significantly, you might choose to re-fix the offset portion at the new lower rate and invest your savings elsewhere. The optimizer helps you model both scenarios.
The optimizer tracks your LVR as you repay principal. When your LVR crosses a tier boundary (80%, 70%, 60%), it automatically applies the lower rate that your bank would offer at renewal. This means projections get more accurate over longer timeframes, not less.