How Rate Lock Agreements Protect You From Rising Interest Rates
From Aaron’s YouTube: “How to STOP your interest rates going UP”
Video not loading? Watch it on YouTube
Posted 17 December 2025
The short version
- Rate lock agreements let you lock in a chosen interest rate before it's applied to your mortgage.
- This protects you if rates rise between when you choose a rate and when it takes effect.
- Most banks offer rate locks for both new mortgages and refinancing situations.
- It's particularly useful when interest rates look likely to increase further.
What is a rate lock agreement?
A rate lock agreement is a simple option banks offer that freezes the interest rate you've chosen for your mortgage. It guarantees that rate won't change before it becomes active, regardless of whether market rates move up or down in the meantime.
In the past when rates were falling, locking didn't make much sense - you'd want the benefit of any drops. But when rates are rising, like now, it protects you from increases during that gap between choosing a rate and it taking effect.
When should you use one?
First home buyers or anyone getting a new mortgage can request a rate lock when finalising their loan structure with their broker or banker. If you've just bought a house and are choosing your rates, this is when you'd tick the rate lock box in your paperwork.
It also works when refinancing existing mortgages. If you've received notification that you need to choose a new rate in 45 days, you can lock in your selected rate immediately rather than risk it rising before the switch happens.
How does it work in practice?
Most (but not all) banks offer rate lock agreements as standard. You'll need to actively choose to use it - it's not automatic. Once locked, your rate is secured regardless of market movements - this gives certainty to your financial planning.
The key is timing. If rates look likely to rise further, locking makes sense. If rates might fall, you're usually better not locking. Your mortgage adviser can help assess whether locking is right for your specific situation and timeline.
This is general information, not personalised financial advice. For advice on your situation, talk to Aaron.
Keep learning
How offset accounts actually work
An offset account links your everyday savings to your mortgage. You only pay interest on the difference.
Paying extra on your mortgage: does it actually work?
Yes, it works. Extra repayments go straight onto the loan balance, and interest is charged on the balance, so every extra dollar stops earning the bank interest for the rest of the loan.
The "special" rate: what 20% deposit actually buys you
The rates NZ banks advertise are usually "special" rates — and the headline condition is at least 20% deposit or equity.
Weekly vs Monthly Repayments: What Actually Saves You Money
Paying weekly instead of monthly doesn't automatically save you money or time on your mortgage
How Extra Repayments Can Save You Years on Your Mortgage
Paying an extra $970/month on a $500k loan at 5% saves 13 years.
How Small Extra Repayments Save Big on Your Mortgage
An extra $5/day ($35/week) on a $650k loan at 7% saves $112,000 interest over 30 years.
Why New Zealand Mortgage Rates Are Increasing
All major NZ banks have now increased their longer-term fixed mortgage rates.
How Your Daily Coffee Could Save You $107,000 on Your Mortgage
Putting just $5 a day extra on a $500k mortgage at 7% saves $107,000 in interest.
3 Times Refinancing Your Mortgage Doesn't Make Sense
Your current bank may already offer the best terms (like offset accounts or discounts) for your situation.
Aaron's 2026 Interest Rate Predictions for NZ Homeowners
Aaron predicts mortgage rates will likely stay flat through 2026 despite recent bank increases.
Why Rising Interest Rates Can Help House Prices Stay Stable
Rising interest rates help keep house prices stable.
The hidden interest-only mortgage trap
Interest-only loans have much higher repayments after the interest-only period ends, as you still repay the full loan over the remaining term.
Offset Accounts vs Revolving Credit: The Key Difference
Offset accounts let you link multiple savings accounts to offset mortgage interest, while revolving credit is one lump sum.
Why the OCR drop hasn't lowered mortgage rates yet
The OCR drop hasn't yet translated to lower fixed mortgage rates.
Your weekly mortgage repayments at current rates
At a 4.49% one-year fixed rate, a $600,000 mortgage costs a specific weekly amount you can plan for.
The surprising impact of an OCR cut on your mortgage
The OCR has been cut, but some economists believe this was the wrong move.
Offset accounts in the real world: the $50,000 example
A $50,000 offset account on a typical NZ mortgage saves around $67 per week in interest.
When Fixed Loan Break Fees Cost Thousands
Fixed term break fees can cost tens of thousands if rates drop significantly.
Latest Fixed Rate Drops: What This Means for Your Mortgage
Six-month fixed rates have dropped to 5.49%.
3 Ways to Pay Off Your Investment Property Mortgage
Principal and interest repayments use both your income and rental income to steadily pay down the mortgage.
How Your Loan Term Affects the Interest You Pay
A 10-year loan term could save you over $500,000 in interest compared to a 30-year term.
3 Reasons Some People Get Cheaper Interest Rates
Borrowers with 20%+ deposits get lower rates than those with smaller deposits.
How a $50,000 Offset Account Saves Interest on Your Mortgage
A $50,000 offset account saves $242,000 in interest over 30 years on a $700,000 mortgage at 5%.
Latest Interest Rate Drops: What It Means for Your Mortgage
The mortgage rate war is heating up as banks compete by lowering their interest rates.
What a $10 Million Mortgage Costs
A $10.05 million purchase needs a $2.1 million deposit (20%).
Refix or Refinance: What’s the Difference?
Refixing means staying with your current bank and locking in a new interest rate when your term ends.
How Lower Test Rates Affect Your Mortgage Borrowing Power
NZ banks have lowered their test rates to around 8%, increasing borrowing power.
Fixed vs. Floating Rates: The Key Differences
Fixed rates are usually cheaper than floating rates and lock in your rate for a set term (e.g. two years at 5%).
Refix vs Refinance: How Much Can You Save on Your Mortgage?
Refixing a $750,000 mortgage from 7% to 4.99% saves over $200 per week.
Should you pay off your mortgage faster? The trade-offs
Faster mortgage payoff saves you interest and gives psychological benefits like feeling in control of your debt.