Guides
Original explainers on pay, deposits, borrowing and mortgages — the rules behind each calculator.
The calculators give you a number. These guides explain the rule that produced it — why a pay rise is taxed the way it is, what a bank actually counts as your deposit, where a debt-to-income cap comes from, and what an extra $50 a fortnight does to a thirty-year mortgage. Each one is original writing, meant to be read on its own without a finance background, and each ends at the tool it relates to.
They are ordered the way the money moves: what you earn, what you save, what you can borrow, and what you repay. If you are working toward a first home, start with the path from payslip to home loan, then read deposit and borrowing guides in order. If you arrived with one specific question — tax codes, First Home Loan, offset accounts, serviceability — skip straight to that guide.
Every rate and threshold quoted in a guide is read from the same rules files the calculators use, so the figures in the prose and the figures in the tools can never drift apart. Where a number comes from a published source — Inland Revenue, the Reserve Bank, Kāinga Ora — that source is named on the reference pages, and how we check and update them is set out in the methodology. These are explanations of how the rules work, not financial advice.
Income
- How PAYE works in New ZealandWhy your gross salary isn't your money: progressive brackets, the ACC levy, KiwiSaver, student loan and the IETC — and how they stack.
- How ACC affects your take-home payThe levy on your payslip that isn't income tax: what the ACC earners' levy pays for, how the cap works, and why high earners stop paying it.
- Tax codes explained for New Zealand payslipsWhat M, ME, SL and the secondary codes actually tell your employer — and what happens if you get the code wrong.
- How student loan repayments change take-home payThe 12% repayment is only on income above the threshold — why the hit feels sudden, and how it interacts with tax and KiwiSaver.
- KiwiSaver contribution rates and take-home payWhat the default employee rate means for your payslip, how employer contributions sit on top, and when a temporary 3% reduction makes sense.
- Independent earner tax credit (IETC) explainedWho gets the IETC, how it abates, why it vanishes around middle incomes, and how the ME tax code claims it through the year.
- Two jobs and secondary tax in New ZealandWhy a second job uses a flat code instead of the brackets, how SB–SA are chosen, and how to stop over- or under-withholding.
- What a take-home pay calculator cannot seeWorking for Families, child support, salary sacrifice, self-employment and one-off deductions — why a model is not a payslip.
Deposit
- Using KiwiSaver for your first homeWhat you can and can't withdraw, the $1,000 you must leave behind, the three-year rule, and the exclusions that catch people out.
- How much deposit do I need?20% is the comfortable answer, 10% is common, 5% is possible — what each level really costs, and where the thresholds come from.
- Saving for a house deposit in New ZealandHow to turn a target deposit into a monthly plan — KiwiSaver, cash, gifts, and the costs that sit beside the headline percentage.
- Kāinga Ora First Home Loan explainedHow the 5% deposit pathway works, who the income caps apply to, why LMI exists, and how it differs from the closed First Home Grant.
- Buying a first home with a partnerWhy each person’s KiwiSaver is assessed separately, how combined income changes borrowing, and what to align before you make an offer.
- Costs of buying a house beyond the depositLegal fees, reports, moving, insurance and the cash buffer lenders like to see — the money that sits beside your deposit percentage.
- How to apply for a KiwiSaver first-home withdrawalThe practical sequence: confirm you qualify, gather the documents, apply through your provider, and time settlement so the funds actually land.
- When you cannot use KiwiSaver to buy a homeSubsequent homes, Australian-sourced amounts, overseas government contributions, and the $1,000 that always stays — the exclusions that surprise people.
- Low-deposit buying and lenders’ mortgage insuranceWhy a 5% or 10% deposit costs more than the cash gap, what LMI is for, and how First Home Loan changes the picture without being a grant.
Borrowing
- DTI and LVR explainedThe two rules that decide how much a bank will lend you — and why your unused credit card limit reduces it.
- What banks count as debt for borrowing powerCredit card limits, student loans, hire purchase and personal loans — the balances and limits that shrink how much you can borrow.
- How banks test mortgage serviceabilityWhy the rate you are quoted is not the rate that decides approval — assessment rates, living costs and the buffer above carded rates.
- From payslip to home loan: the full pathHow take-home pay, KiwiSaver, deposit, borrowing range and repayments connect — the order to run the numbers before you shop for listings.
- Proving income to a New Zealand bankPayslips, employment letters, bonuses, contractors and parental leave — what lenders actually accept, and why a calculator range is not an assessment.
- How bonuses and overtime change borrowing powerWhy a large bonus on a payslip often counts as half — or nothing — in a mortgage assessment, and how to enter income without fooling yourself.
Mortgage
- Offset accounts and extra repaymentsWhy small extra payments early save disproportionate interest, and how an offset balance works without locking your money away.
- Weekly vs fortnightly repaymentsWhy fortnightly repayments can shorten a mortgage term, when they do not, and how to separate marketing from the maths.
- Fixed vs floating mortgage rates in New ZealandCertainty versus flexibility, break costs, extra repayments, and how to think about the choice without pretending anyone can call the OCR.
- Choosing a mortgage term: 20, 25 or 30 yearsHow term length changes repayments and total interest, and how to pick a term you can actually sustain when rates move.
- How mortgage offset accounts work in New ZealandInterest calculated on loan minus offset balance, why emergency funds fit there, and how offset compares with paying the loan down.
- Mortgage break fees on a New Zealand fixed rateWhat a break cost actually is, when it appears, why it can be large even on a small remaining term, and how to think about fixing without pretending you can call rates.
Last updated · 24 July 2026
Rates and thresholds are listed with official sources on the methodology and reference pages.
Every number traces to an official source.
Rates and thresholds come from published IRD, Reserve Bank and Kāinga Ora rules — each shown with its source and the date it was last checked.