What is a mortgage refinance break-even calculation?

It is the point at which the money you save each month from a lower interest rate has paid back what refinancing cost you: the break fee, legal fees and valuation fee, minus any cashback the new lender offered. Divide your net switching cost by your monthly saving to get the number of months to break even. Refinancing generally makes sense if you plan to stay with the new loan well beyond that point.

How much does it cost to refinance a mortgage in NZ?

Typical refinance costs in New Zealand include legal or conveyancing fees to discharge the old mortgage and register the new one, commonly around $1,600, and a registered valuation the new bank usually requires, typically $700 to $1,200. If you are still inside a fixed-rate term you may also owe a break fee to your existing bank. Many banks offer their own cashback to offset some of this, which reduces your net cost.

What is a mortgage break fee and when do I pay one?

A break fee, also called an early repayment charge, applies when you exit a fixed-rate loan before the fixed term ends and wholesale interest rates have fallen since you fixed. Banks broadly calculate it as your loan balance multiplied by the difference between your fixed rate and the current wholesale rate, multiplied by the years remaining on your fixed term, plus any administration fee. You do not usually pay a break fee on a floating loan, or once your fixed term has already expired. Use the Mortgage Break Fee Calculator on this site for a detailed estimate.

Do NZ banks offer cashback for refinancing?

Yes. New Zealand banks periodically offer a cash contribution, either a flat dollar amount or a percentage of the loan, to attract refinance business. Offers change often and vary by bank, loan size and how competitive lending is at the time, so ask your bank or a mortgage adviser what is currently available before you decide. Some banks apply a clawback if you leave again within an agreed period, similar in effect to a break fee.

Is it worth refinancing if I am still in a fixed term?

It can be, if the interest saving from the new rate is large enough to clear the break fee and other switching costs within a timeframe you are comfortable with. The break-even figure from this calculator tells you exactly how many months that takes. If you plan to stay in the new loan well beyond the break-even point, refinancing early can still make sense even after paying a break fee.

What is the difference between refinancing and refixing?

Refixing means choosing a new fixed rate with your current bank when your existing fixed term ends, with no new application, no valuation, and usually no legal fees. Refinancing means moving your mortgage to a different bank, which involves a full loan application, a registered valuation, legal work to discharge the old mortgage and register the new one, and potentially a break fee if you switch mid-term. Refinancing costs more up front but can be worthwhile if another bank's rate, terms or cashback offer is significantly better.

Does refinancing affect my loan-to-value ratio (LVR)?

Refinancing itself does not usually change your LVR if you borrow the same amount against the same property value. The new bank will reassess your LVR using its own registered valuation, which may come in higher or lower than your last one, and Reserve Bank LVR restrictions apply to the new loan as if it were a fresh application. A lower valuation than expected can affect the rate or terms on offer.

Are there tax implications from refinancing a rental property?

Since 1 April 2025, mortgage interest on residential rental property is fully deductible again in New Zealand, so refinancing a rental to a lower rate simply reduces your deductible interest expense and, in most cases, your taxable rental income. Costs like legal fees and the valuation fee connected to refinancing an existing loan can be treated differently from interest for tax purposes, so check the deductibility of specific refinancing costs with an accountant.

Mortgage Refinance Calculator

Quick answer: Refinancing is worth it once your monthly saving from a lower interest rate repays the cost of switching: break fee (if any), plus legal and valuation fees, minus any cashback. Enter your loan balance, remaining term, current and new rate, and your switching costs below to see your exact break-even point in months.

This mortgage refinance calculator works out whether switching your home loan to a new interest rate, whether with your current bank or a different lender, is genuinely worth the cost of making the change. Enter your remaining loan balance, the remaining term left on the loan, your current interest rate and the new rate you have been offered, and it works out your monthly repayment under both side by side, along with the difference between them. Then enter the costs of switching: any break fee your current bank charges for exiting a fixed rate early, the legal fee a lawyer charges to discharge your old mortgage and register the new one, commonly around $1,600, and the valuation fee the new lender typically requires, commonly $700 to $1,200, minus any cashback incentive the new bank is offering you. The calculator adds these costs together, nets off the cashback, and divides the result by your monthly saving to show the exact number of months it takes to break even. It also shows the total interest you would save over the remaining term if you kept making the same repayment schedule. It updates instantly as you type, with no need to press a button. This is useful for anyone comparing a refinance offer, deciding whether to break a fixed term early, or simply checking that a lower advertised rate is genuinely worth the paperwork and cost of switching banks. Figures are indicative estimates only, so confirm your specific costs with your current bank, the new lender and a mortgage adviser before you commit.

Calculate.co.nz is proud to be partnered with Premium Homes, a recognised leader in eco-friendly, sustainable, and energy-efficient homebuilding. With a dedicated team and award-winning experience, they create homes that prioritise health, comfort, and long-term performance. Their founders, Andrew and Kelly, set out to raise the standard of residential construction in New Zealand by combining practical building expertise with a clear commitment to doing things better for homeowners.

Updated July 2026 Current rates and legislation applied.

Verification & Methodology

Repayment formula: Standard table (principal and interest) loan amortisation formula, comparing your current rate and the new rate on the same remaining loan balance and remaining term.
Typical switching costs used as defaults: Legal/conveyancing fee of approximately $1,600 and a registered valuation of $700 to $1,200 (midpoint $900 used as the default). These are indicative New Zealand market costs, not government fees, and vary by law firm, valuer and region. Adjust them to your own quotes.
Break fee: Entered directly by you, since it depends on your bank, your fixed rate, the current wholesale rate and your remaining fixed term. Use the Mortgage Break Fee Calculator on this site for a detailed estimate.
Cashback: Entered directly by you. NZ bank cashback offers change frequently and are not a fixed government rate, so confirm the current offer with your lender or adviser.
Rental interest deductibility: 100% of mortgage interest on residential rental property has been deductible again since 1 April 2025 under the Income Tax Act 2007, relevant if you are refinancing an investment property.
Last verified: July 2026, against current bank refinancing practice and Inland Revenue guidance.
Source data: Inland Revenue, residential rental interest deductibility; typical legal and valuation cost ranges reflect current New Zealand conveyancing and registered valuation market rates.

Remaining Loan Balance

Remaining Loan Term

years

Current Interest Rate

New Interest Rate on Offer

Cost of Switching Break Fee (if exiting a fixed term early)

Leave at 0 if you are on floating or your fixed term has already ended. See the Mortgage Break Fee Calculator for an estimate. Legal / Conveyancing Fee

Valuation Fee

Cashback from New Lender

$0.00

Monthly Saving

0.0 mo

Break-even Period

Enter your loan details and switching costs above to see your break-even point.

Current monthly repayment

$0.00

New monthly repayment

$0.00

Total switching cost (break fee + legal + valuation)

$0.00

Less cashback from new lender

-$0.00

Net switching cost

$0.00

Total interest saved over remaining term (same repayment schedule)

$0.00

Net lifetime saving after refinancing costs

$0.00

What to do next: If your break-even period comes out under 12 to 24 months and you plan to stay in the new loan beyond that point, get a mortgage adviser to confirm the actual break fee, the current cashback offer, and the total legal cost from your bank and the prospective new lender before you commit, since all three figures vary by bank and change often. A broker works across multiple lenders and can usually negotiate a larger cashback or a sharper rate on your behalf, generally at no direct cost to you.

What Refinancing a Mortgage Actually Costs in New Zealand

Refinancing means moving your home loan from one lender to another, rather than simply choosing a new rate with your current bank. That move brings a handful of real costs on top of whatever rate you are offered. If you are still inside a fixed-rate term with your current bank, you may owe a break fee (also called an early repayment charge) to compensate the bank for the wholesale funding it locked in on your behalf. The new bank will generally require a registered valuation of your property, typically costing $700 to $1,200 depending on the valuer and location, and you will need a lawyer to discharge the old mortgage and register the new one, which commonly costs around $1,600 in legal fees. Working against these costs, many banks offer a cash contribution, sometimes called a cashback, to attract your business, which can range from a flat dollar figure to a percentage of the loan. None of these figures are fixed by law or regulation, so the numbers above are indicative defaults you should replace with your own actual quotes once you have them.

How This Calculator Works Out Your Break-Even Point

The calculator uses the standard table loan formula to work out your monthly repayment under your current rate and under the new rate, on the same remaining loan balance and the same remaining term, so the two figures are directly comparable. The difference between them is your monthly saving. It then adds together your break fee, legal fee and valuation fee to get your total switching cost, subtracts any cashback the new lender is offering, and divides the result by your monthly saving. That gives you the break-even period in months, the point at which your accumulated monthly savings have fully repaid what refinancing cost you. Every dollar saved after that point is a genuine net gain. The calculator also shows the total interest you would save over the remaining term if you kept making the same size repayments, and a net lifetime saving figure once the switching cost has been deducted from that interest saving.

Break Fees: When You Pay One, and When You Don't

A break fee only applies while you are still inside a fixed-rate term and the wholesale interest rate has moved in the bank's favour since you fixed. Banks broadly calculate the fee as your loan balance multiplied by the difference between your original fixed rate and the current wholesale rate, multiplied by the years remaining on your fixed term, plus any flat administration fee. If wholesale rates have risen since you fixed, or your fixed term has already expired and you are on floating, you generally will not owe a break fee at all, and this field can be left at zero. Because the exact figure depends on your bank's specific wholesale funding cost on the day you break, the dedicated Mortgage Break Fee Calculator on this site walks through that calculation in detail and is the better tool for pinning down that one number before you bring it back here.

Refinancing vs Refixing

It is worth being clear about the difference between refinancing and simply refixing. Refixing means choosing a new fixed rate with your existing bank once your current fixed term ends. There is no new application, no valuation, and usually no legal cost, so refixing to a lower rate is close to pure saving with no switching cost to recover. Refinancing means moving the loan to a different bank entirely, which triggers a full credit application, a registered valuation, legal work on both ends of the transaction, and potentially a break fee if you switch before your fixed term is up. Refinancing therefore needs a genuinely better outcome, whether that is a materially lower rate, better terms, or a worthwhile cashback offer, to justify the extra cost and paperwork over simply refixing with your current bank.

Worked Example

Karl and Priya have $500,000 remaining on their mortgage with 25 years left on the term. Their current bank's rate is 6.85%, and a competing bank has offered them 5.65% to switch. On the same $500,000 balance and 25-year term, their current repayment works out to $3,486.20 a month, and the new rate would bring that down to $3,115.39 a month, a saving of $370.81 every month. To switch, their current bank would charge a $2,500 break fee, since they are partway through a fixed term and wholesale rates have fallen. Add a $1,600 legal fee and a $900 valuation fee, for a total switching cost of $5,000. The new bank is offering $2,000 cashback, which brings their net switching cost down to $3,000. Dividing that $3,000 by their $370.81 monthly saving gives a break-even period of just over 8 months. If Karl and Priya intend to stay in the new loan for anywhere near the rest of its 25-year term, which is the case for most refinances, the saving is overwhelming: kept up over the full remaining term at the same repayment level, the lower rate saves roughly $111,242 in total interest, or about $108,242 once the $3,000 net switching cost is deducted.

Who This Calculator Is For

This calculator suits anyone who has been offered a new mortgage rate, whether from their current bank or a competitor, and wants to know if switching is genuinely worth the cost and hassle involved. That includes homeowners approaching the end of a fixed term who are comparing a refix offer against refinancing elsewhere, borrowers considering breaking a fixed term early to lock in a materially lower rate, and anyone weighing up a bank's cashback offer against the legal and valuation costs of moving their loan. It is a break-even and saving estimate rather than a full loan application, and it does not model changes to your loan structure, such as switching from principal and interest to interest-only, or restructuring into multiple fixed splits.

What This Calculator Assumes

Your current and new repayments are compared on the same remaining loan balance and the same remaining term, so the saving reflects the rate change alone.
Repayments follow a standard table (principal and interest) amortisation schedule, not interest-only.
Default legal fee (~$1,600) and valuation fee ($700 to $1,200, $900 used as the default) are indicative New Zealand market costs, not fixed or government-set figures, and should be replaced with your own quotes.
Break fee and cashback are entered by you, since both are specific to your bank, your fixed rate history, and the current lending market.
Results are indicative estimates only, exclude any change in loan structure, and are not financial advice. Confirm final figures with your bank, the new lender and a mortgage adviser before switching.

Related Mortgage Calculators

Mortgage Break Fee Calculator: work out the early repayment charge for exiting a fixed-rate loan before it ends.
Mortgage Refix Savings Calculator: interest saved by refixing to a new rate with your current bank, no switching costs involved.
DTI Income Multiple Calculator: check a new loan amount against the RBNZ 6x/7x debt-to-income speed limits.
Fixed vs Floating Mortgage Calculator: compare the cost and flexibility of fixed and floating rates.
Mortgage Calculator: work out repayments on any loan amount, rate and term.

Official NZ sources

This calculator is built from primary New Zealand sources. Always confirm current figures against the official source for your situation:

Inland Revenue (IRD) – mortgage interest deductibility for residential rental property
Reserve Bank of New Zealand – macroprudential policy overview (LVR and DTI restrictions on new lending)
Commerce Commission – consumer guidance on mortgages and switching lenders

If you've found a bug, or would like to contact us, or learn more about James Graham and Calculate.co.nz.

Calculate.co.nz is partnered with Interest.co.nz for New Zealand's highest quality calculators and financial analysis.

Calculate.co.nz is the sister site of CalculatorHub.com, the world's largest calculator website by tool count.

All calculators and tools are provided for educational and indicative purposes only and do not constitute financial advice.

Calculate.co.nz is proudly part of the Realtor.co.nz group, New Zealand's leading property transaction literacy platform, helping Kiwis understand the home buying and selling process from start to finish. Whether you're a first home buyer navigating your first property purchase, an investor evaluating your next acquisition, or a homeowner planning to sell, Realtor.co.nz provides clear, independent, and trustworthy guidance on every step of the New Zealand property transaction journey.

Calculate.co.nz is also partnered with Health Based Building and Premium Homes to promote informed choices that lead to better long-term outcomes for Kiwi households.

Calculate.co.nz is hosted in Auckland by SiteHost New Zealand.

All content on this website, including calculators, tools, source code, and design, is protected under the Copyright Act 1994 (New Zealand). No part of this site may be reproduced, copied, distributed, stored, or used in any form without prior written permission from the owner.

About & trust: Why Calculate is NZ's most comprehensive · By the Numbers · How we compare · Editorial standards · How we keep data current · NZ finance glossary · Research & data · Financial literacy NZ · About · Privacy policy · Terms of use

Reviewed and maintained. Last reviewed 2026-07-27 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.