2 Bank Account Tips the Banks Will Never Tell You
Banks are businesses. Like any company, their mission is to grow profits and build market share—not necessarily to give you advice that helps you borrow from a competitor.
That’s why there are some helpful banking strategies they’ll never suggest. At Mortgage Lab, we often share the following two tips with clients—because they can make a big difference when applying for a mortgage.
Tip 1: Couples Should Put Their Income Into Different Banks
In recent years, the Reserve Bank of New Zealand has introduced stricter rules for mortgage lending. These include:
LVR restrictions to limit high-risk borrowing
Responsible Lending Code requirements to ensure banks lend safely
Test rates of around 8% to assess whether you could handle future interest rate rises
Assumptions like 25% vacancy on rental properties, to account for gaps in tenancy or extra costs
These policies particularly affect borrowers in the “grey zone”—those on the edge of the bank’s lending comfort. Examples include:
Past credit issues (even if resolved)
Borrowing over 80% of the property’s value
Heavy reliance on rental or benefit income
Self-managed new builds
These aren’t dealbreakers on their own, but banks are cautious. And they don’t want to be seen as the go-to for borderline applications.
So how do banks decide which grey-zone loans to approve?
Ask any mortgage adviser, and you’ll hear the same thing: banks favour existing customers. They know more about them and can justify their decisions more easily.
What counts as an “existing customer”?
Banks typically define this by where your salary is deposited. If you’re paid into a bank account, they consider you one of their own—but only if those deposits have been going in for at least three to six months.
So no, you can’t just switch your salary over the week before applying and expect a warm welcome.
Should couples bank together?
Here’s the tip: split your salary deposits between two different banks.
You can still have a joint account for shared expenses, but if each partner is paid into a different bank, you’re both considered “existing customers” at separate banks. This gives your mortgage adviser two solid lending options to work with.
It’s a small move that could make a big difference when you're right on the edge of lending policy.
Tip 2: Keep Your Business Banking Separate from Your Mortgage
Running a business is unpredictable—and banks know this. That’s why most banks have staff specifically assigned to monitor business accounts, especially when a customer has a business loan or mortgage.
Let’s say you’ve set up a Revolving Credit facility as a safety net, with $20,000 or more available for quiet months. This buffer is useful—but here’s the catch: if your business slows down and the bank sees warning signs in your accounts, they can cancel that limit without warning.
And yes, this tends to happen exactly when you need it most.
Why? Because they’re watching.
If your business account is at the same bank as your mortgage, that lender has a front-row seat to how your business is performing. They might act to “protect” you by cancelling lending access—based on their own interpretation of risk.
Real Example
One Mortgage Lab client had a $300,000 Revolving Credit facility tied to a property. He used it as a buffer for his business. One day, he logged in and saw the facility was gone.
When he called the bank, they told him they had heard about a slow quarter… and proactively removed the limit. The kicker? The “heads-up” didn’t even come from him—it came from his business partner.
Was this a cautious Business Manager or a bank-wide policy? Hard to say. Either way, a different bank was happy to pick up the mortgage and reinstate the credit facility.
Summary
Tip 1: If you’re a couple planning to buy a home—especially with less than 20% deposit—consider having your salaries go into different banks. This can open more mortgage options when it counts.
Tip 2: If you own a business, it’s worth keeping your business accounts separate from your mortgage lender. It’s a simple way to protect access to your lending facilities.