Mortgages, the plain version.

For an existing home, lenders usually look for around a 20% deposit, though lower-deposit lending exists — banks are allowed a limited share of higher-risk, low-deposit loans, and new-builds are often treated more favourably.

The rules around low-deposit lending and loan-to-value limits change with Reserve Bank settings, so check the current position rather than relying on a figure. A bigger deposit generally means a better rate and less to repay, so it's worth building where you can.

Lenders weigh your income against your existing commitments — other debts, credit card limits and living costs — and stress-test your repayments at a rate higher than the one you're offered, to be sure you could handle rate rises.

So two people on the same income can borrow very different amounts. Tidying up credit card limits and other debt before you apply usually lifts what you can borrow. A mortgage adviser can give you a realistic number for your situation.

A fixed rate is locked for a set term — often six months to five years — so your repayments don't change during that period, even if rates move. A floating (variable) rate can change at any time, up or down, and usually lets you make extra repayments freely.

Many people split their loan, fixing part for certainty and floating part for flexibility. There's no universally right answer; it depends on whether you value predictable repayments or the freedom to pay down faster.

Pre-approval is a lender's conditional agreement to lend you up to a certain amount. It tells you your budget and shows sellers you're serious.

You apply through a bank or mortgage adviser with proof of income, savings and expenses. It usually lasts a few months, and it's worth having before you look seriously — especially if you might buy at auction, where there's no finance cooling-off.

A mortgage adviser works across several lenders, so they can compare options and find one that fits, and they usually don't charge you directly — they're paid by the lender. Going straight to your bank means one set of products and criteria.

An adviser is especially useful if your situation is less straightforward — self-employed, a smaller deposit, or some debt to work around. Since lending isn't something we advise on, a good mortgage adviser is exactly who we'd point you to.

Both cut the interest you pay by keeping your savings working against the loan. A revolving credit account works like a big overdraft — your pay goes in, reducing the balance you're charged interest on. An offset mortgage links your savings accounts to the loan, so those balances reduce the interest without being locked away.

Used with discipline they save real interest and time. Used loosely, the flexibility makes it easy to never actually pay the loan down, so they suit people who are organised with money.

The biggest levers are paying more than the minimum and paying more often. Even small extra repayments early cut years off the loan, because you're attacking the balance before decades of interest pile on.

Other moves help: keeping repayments the same when you refix to a lower rate, making lump sums when you can, and using an offset portion for everyday cash. Check for fixed-rate break costs first, since some fixed loans limit how much extra you can pay.

When your fixed term ends, you refix at whatever rates are then on offer. If rates have risen, your repayments go up — sometimes noticeably — which is exactly why lenders stress-test you at higher rates up front.

The way to stay ahead of it is to know when your fixed term ends and plan for it, rather than be surprised. If a higher repayment would stretch you, model it before it happens — one good reason not to borrow right up to your absolute limit.

The deposit is the big one, but budget for the extras: a lawyer or conveyancer, a builder's report and/or valuation, moving costs, and often a LIM report. There's no stamp duty in New Zealand, which helps.

Then there are the ongoing costs — rates, insurance, maintenance, and body corporate fees for apartments or units. Padding your budget for these means the first surprise bill doesn't land on a credit card.

The mortgage doesn't pause because you're sick or injured — the repayments keep coming whether or not you can earn. That's the single biggest financial risk of taking on a large home loan.

It's why cover that protects your repayments matters so much once you buy. This is the point where lending and the advice we do give meet — see our mortgage protection and income protection pages.