Mortgage Pre-Approval Expiry Calculator NZ
A pre-approval is easy to misread in two directions at once. It gets treated as a guarantee, which it is not, and as a purchase price, which it also is not. What the letter actually says is that a lender has looked at you rather than at a house, and would be prepared to advance a certain amount subject to conditions, for a limited period. Two things follow from that. The first is the clock, because an approval that lapses in the middle of a negotiation is a genuine problem and a renewal is a fresh assessment rather than a formality. The second is that the approved amount is only half of your buying position: the loan to value limit means your deposit has to cover the rest of the price, and for a lot of buyers it is the deposit that runs out first, so a bigger approval buys nothing at all.
The clock
Start a renewal before the approval lapses. A renewal requested while it is still live is usually a lighter process than one requested afterwards.
What the approval actually buys
Both limits land in the same place, so your deposit and your approval are matched. Saving more and borrowing more would both move the ceiling.
If you use the whole approval period
| Today | At expiry | |
|---|---|---|
| Deposit | $150,000.00 | $152,000.00 |
| Approved loan | $600,000.00 | $600,000.00 |
| Loan to value at the ceiling price | 80.00% | 79.79% |
| Most you can pay | $750,000.00 | $752,000.00 |
Waiting until expiry adds $2,000.00 to the deposit and $2,000.00 to what you can pay.
The approval is the loan, not the price
The most common misreading of an approval letter is to treat the number as a budget for a house. It is not: it is the maximum the lender will advance, and the purchase price is that plus whatever you put in yourself. The complication is that the two are not independent, because the loan to value limit ties the loan to the price. If the loan can only be eighty per cent of the price, then your deposit has to be at least twenty per cent, and a deposit that falls short caps the price no matter how large the approval is. That is why this calculator shows both ceilings and then takes the lower one. When the deposit is the binding constraint, negotiating a bigger approval achieves nothing, and the only lever that moves is saving.
Why a renewal can come back smaller
Renewing feels administrative and is not. The lender reassesses your income, your commitments, your credit position and the property policy that applies at the time, and it does so against its own servicing test rate rather than the rate you would actually pay. Any of those can move. A new car loan, a credit card limit that was never cancelled, a change in hours, or an increase in the test rate can all reduce the number, and none of them feels like a change in your ability to pay. The practical consequence is that the last few weeks of an approval are the wrong time to discover the problem, and starting the renewal early is worth more than it costs.
An approval is not a safe basis for bidding at auction
A pre-approval is conditional on a valuation of the particular property, and an auction bid is unconditional the moment the hammer falls. Those two facts do not sit together. If the valuation comes in below the price you bid, the shortfall is yours to cover, and you are already contractually bound. Buying at auction sensibly means having the property specifically approved beforehand, not relying on a general approval that has never seen the house.
Worked example
A pre-approval for $600,000.00 is issued on Monday 15 June 2026 and runs for 3 months, so it expires on Tuesday 15 September 2026. Working it out on Friday 7 August 2026, 53 days have been used and 39 days remain.
With $150,000.00 saved and a loan to value limit of 80%, the approval on its own would support a price of $750,000.00, and the deposit under the LVR limit also supports $750,000.00. The lower of the two is $750,000.00, so that is the ceiling.
Only one whole month of saving is left before expiry, so at $2,000.00 a month the deposit reaches $152,000.00 and the ceiling $752,000.00, an increase of $2,000.00. Part months are ignored, because a month of saving that has not happened yet is not money you can settle with.
How this is calculated
The expiry date is the issue date plus the validity period in months, and the days used and days remaining are counted in calendar days from the date you are working it out. The price the approval alone would allow is the approved loan plus your deposit. The price the loan to value limit allows is your deposit divided by the deposit share of the price, which is one minus the LVR limit, since the deposit has to fund that share. The ceiling is the lower of those two, and the calculator names which one binds. The position at expiry repeats the same arithmetic with the deposit grown by your monthly saving multiplied by the number of whole months remaining, holding the approved loan constant, since the approval amount does not increase on its own.
Official sources
- Loan to value ratio restrictions, Reserve Bank of New Zealand
- Getting a mortgage, Sorted
- Debt to income framework, Reserve Bank of New Zealand
Related NZ calculators
- Borrowing Capacity Calculator for what a lender is likely to approve
- Deposit Required by LVR Band for the deposit each band needs
- Auction Day Cash Required Calculator if you are bidding rather than negotiating
- Deposit Gap Calculator if the deposit is what is holding you back
- Mortgage Pre-Approval, the guide behind this calculator
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