First-home finance is one pipeline. People get stuck when they jump straight to listings or straight to a mortgage repayment without knowing the deposit and the ceiling. FinLab's tools are ordered the way the money moves.
1. Know what you keep
Start with take-home pay. Tax brackets for 2026-27, ACC at 1.75% up to $156,641, KiwiSaver and any student loan decide the cash you can actually save. A gross salary headline is not a budget.
2. Measure the deposit
Add withdrawable KiwiSaver (after 3 years, minus $1,000), cash, and documented gifts. Compare that total to 5%, 10% and 20% of a realistic price band in your city — not a dream listing.
3. Find the borrowing ceiling
Use income, debts, cards and dependants to estimate a range under DTI and serviceability logic. Remember LVR: deposits under 20% push you into rationed high-LVR territory unless you use an exempt pathway such as a qualifying First Home Loan.
4. Test the repayment
Take a mid-range loan amount into the mortgage calculator. Check fortnightly repayments at the quoted rate and at a higher stress rate. If the stress rate breaks you, the price band is wrong — not merely “tight.”
Compare that repayment against your current rent rather than against your income, because rent is the expense the mortgage replaces and the difference is the real change to your monthly life. Then add the costs that arrive with ownership and do not exist for a tenant: rates, house insurance, body corporate levies if the property has them, and a maintenance allowance for the year the fence or the hot water cylinder fails. A repayment that matches your rent exactly is not a like-for-like swap; it is a meaningful increase in what the roof over your head costs.
5. Only then shop
With a price ceiling, a deposit plan and a repayment you can defend, listings become a filter instead of a temptation. Revisit the numbers when rates, income or KiwiSaver balances change materially. The path is iterative, but the order stays the same.
Why the order matters
Each step feeds the next, so running them out of sequence produces confident answers to the wrong questions. A repayment figure is meaningless until you know the loan size, the loan size depends on the deposit and the ceiling, and both depend on what your payslip actually leaves you. Buyers who start at step four typically arrive at an affordable-looking repayment on a loan they cannot be approved for. Buyers who start at step one usually find the answer less exciting and considerably more useful.
The most common failure is treating the ceiling as the target. The borrowing range tells you what a lender might allow, which is a limit, not a recommendation. Borrowing to the top of it leaves nothing for the rate rise, the redundancy or the roof. A price band comfortably inside the ceiling is not a failure of ambition — it is the difference between owning a house and being owned by one.
What to gather before you start
The whole sequence takes about an hour if you have the inputs to hand: a recent payslip showing gross pay, tax code, KiwiSaver rate and any student loan deduction; your current KiwiSaver balance and the date you joined; the balance and minimum payment on every debt, plus the limit on every credit card and overdraft, whether or not you use them; and a realistic sale price range for the kind of property you are actually looking at, taken from recent sales rather than asking prices.
Where the numbers will move
Three things change the picture often enough to be worth rechecking. Interest rates, which alter the repayment and the rate at which you are assessed. Your KiwiSaver balance, which grows with contributions and returns, and which is only withdrawable once the 3-year membership test is met. And your debts — clearing a car loan or reducing a card limit can shift the ceiling more than a modest pay rise. Rerun the sequence when any of these move, rather than carrying an estimate from six months ago into a negotiation.