Mortgages

4 min read16 Jul 2025

How do I fix my mortgage interest rate?

Author: Peter Norris

Mortgage broker for over 10 years, property investor and Managing Director at Opes Mortgages

Reviewed by: Ed McKnight

Resident Economist, with a GradDipEcon and over five years at Opes Partners, is a trusted contributor to NZ Property Investor, Informed Investor, Stuff, Business Desk, and OneRoof.

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So, your mortgage is about to expire, and the bank wants you to “re-fix”.

Easy, right? Just choose a rate. Hit confirm. Done.

But suddenly you’re scrolling through half a dozen options, wondering: “Should I fix for 1 year, 2 years, 5 years – what’s the best one for me?”

In this article, you’ll learn the exact process and timelines for how to re-fix your interest rate. That includes when to re-fix your interest rate … and what you need to do at each step.

What does “re-fixing” actually mean?

Re-fixing just means choosing a new interest rate.

When you have a fixed-term mortgage you lock in your interest rate for a set period – say 1 year, 18 months or 5 years.

Each term has a slightly different rate, so the bank might offer 4.9% for 1 year or 5% for 18 months.

Once that fixed term ends, your mortgage will automatically roll onto a floating rate. This is usually a more expensive rate.

So to avoid paying that … you can re-fix your interest rate. That means you can lock in your rate for as little as 6 months … or up to 5+ years.

Your bank usually offers a few options, and you simply choose the one that suits you.

More from Opes:

Example: Which interest rate should I use?

Choosing the right term can be tricky. There’s a bit of strategy involved.

Let’s say you needed to re-fix when interest rates were high – the 1-year rate might have been over 7%, while the 5-year rate was lower (around 6%).

So, you might have been tempted to grab the cheaper 5-year rate.

But most mortgage brokers thought rates would fall. So choosing the cheaper 5-year rate could’ve meant paying more over the long run, because then you missed out on the cheaper rate a few years later.

Or maybe you decide to lock in for 3 years, but then you sell your property in a year.

At that point you’ve still fixed your interest rate for another 2 years so you might need to pay a break fee (depending on whether interest rates have dropped).

So if you’re planning to sell you might fix for a shorter time, even if it’s slightly more expensive today.

While it’s tempting to go for the lowest number, it’s often smarter to match your mortgage strategy to your life plans.

Now, if you have no idea what I just said … don’t worry … you’re not supposed to. That’s why sometimes you’ll need advice, and I’ll get to that in a second.

How to re-fix your mortgage interest rate

Most banks will send you a reminder email 30–60 days before your fixed rate expires.

Some let you re-fix through their app or website. A few will call you to see if you need help.

But here’s the thing: your bank won’t automatically give you advice on which rate to lock in, not unless you go looking for it.

They won’t ask if you’re selling, restructuring, heading off on maternity leave, or navigating market uncertainty.

They’ll give you options (“here are our rates”) but not guidance on which one to choose.

And if you don’t take action? Your loan usually rolls onto the floating rate – which is typically more expensive.

That’s why many Kiwis decide to re-fix their interest rate with a mortgage adviser.

How to re-fix your interest rate with a mortgage adviser

Whether you got your mortgage through us at Opes Mortgage (or not) … you can still ask for our help choosing an interest rate.

Here’s how it usually works.

If you got your mortgage through us – around 45 days before your re-fix is due we’ll email you.

You will get a video update from the team explaining what interest rates we currently see.

Then you can book in a free 15-minute meeting with one of our mortgage advisers. They’ll help you choose how long to fix for (e.g. 6 months, 1 year, 2 years).

And whether now’s a good time to lock in a short or long-term rate.

You can then also talk about if it’s time to change up your mortgage. For instance, you might decide to split your mortgage into chunks to spread your interest rate risk.

Or you might add a revolving credit to pay off your mortgage faster.

You’ll also talk about your plans, like moving house or taking parental leave, because these could impact how long you decide to fix for.

We reckon this is the right thing to do so you make the best choice for your situation.

All of this is free to you. We get paid by the bank because if we help you fix your interest rate that saves them a job.

What if I didn’t get my mortgage through Opes Mortgages? Can you still help?

Even if you didn’t get your mortgage through us, we can still help you re-fix your interest rate.

Here’s how it usually works. If your mortgage is coming up for re-fix:

Send us your bank’s current rates – we’ll check to see if we can beat them
Book a free 15-minute meeting to get advice
We’ll handle the rest

Should I bother with a mortgage broker?

You might think: “Why don’t I just go to the bank directly? Why use a mortgage adviser?”

You don’t just use a broker to see if you can get a better rate. It’s about getting advice and choosing the right rate for you.

A good broker looks beyond numbers and should consider your goals and what’s happening in the market.

For example, in recent years the 1-year rates were high and the 5-year rates were a bit lower.

But with the benefit of hindsight, locking in for 5 years wasn’t the right option for most Kiwis because that could have cost them a lot more.

A good mortgage adviser can see that coming and can give you the right advice and ultimately save you money.

Peter Norris

Mortgage broker for over 10 years, property investor and Managing Director at Opes Mortgages

Peter Norris, a certified mortgage adviser with 10+ years of experience, serves as the Managing Director at Opes Mortgages. Having facilitated over $1.2 billion in lending for 2000+ clients, Peter is a respected authority in property financing. He's a frequent writer for Informed Investor Magazine and Property Investor Magazine, while also being recognized as BNZ Mortgage Adviser of the Year in 2018 and listed among NZ Adviser's top advisers in 2022, showcasing his expertise.

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