Revolving Credit Facilities Explained: A Really Useful Tool for Disciplined Savers

A quick heads-up: The information in this article is designed as a general educational guide only and does not constitute personalised financial, tax, or legal advice. Because everyone's situation is unique (and bank policies change frequently), we recommend speaking with a licensed Financial Adviser to see how this applies to your specific circumstances. For full transparency on our terms of service, how we are remunerated by lenders, and any specific situations where a fee may apply, please read How We Get Paid.

Imagine if your mortgage and your everyday transactional bank account were merged into one.

For most New Zealanders, a home loan is a very rigid, locked-down product. You owe the bank a massive sum of money, and every fortnight, a set amount is automatically deducted from your account. You cannot easily touch that money again, and if you want to pay extra, there are often strict rules or penalty fees capping how much you can contribute.

But what if your mortgage acted exactly like a giant overdraft?

Enter the Revolving Credit Facility. It is one of the most flexible, powerful, and often misunderstood financial tools available in the New Zealand banking system. When used correctly with iron-clad discipline, it can shave years off your mortgage and save you tens of thousands of dollars in interest. When used poorly, it can become a devastating financial trap.

Here is a complete guide to how revolving credit works, the daily interest secret, and how to know if you have the discipline to handle it.

The mechanics: it is just one everyday account

Think of a standard mortgage as a one-way vault. You push money in, but you cannot easily get it back out.

A revolving credit facility is completely different. It is essentially an everyday transactional bank account that comes with a massive, pre-approved overdraft limit secured against the equity in your home.

You actually get an EFTPOS or Visa Debit card attached to this account. Your salary can be paid directly into it. Your power bill, groceries, and streaming subscriptions can be paid directly out of it.

There are no set, mandatory weekly mortgage repayments. You can draw the balance all the way up to your maximum limit, pay it all the way down to zero, and redraw that cash again whenever you like.

The secret is daily interest

Here is where the financial advantage lies. Unlike a standard fixed mortgage, the interest on a revolving credit facility is calculated daily based on the exact balance of the account at midnight, and then charged to your account once a month.

The water tank analogy (see it in action)

The easiest way to understand this is to picture a giant water tank.

• The total size of the tank is your Revolving Credit Limit.
• The water you pour into the tank represents your Available Cash.
• The empty air sitting at the top of the tank is your Net Debt—and that empty space is the only part the bank charges you interest on.

We built the interactive simulator below so you can physically see how this works. Try typing a $2,000 transaction into the simulator and hitting Deposit or Spend. Watch how moving funds in and out of the account instantly changes your "Daily Interest Charged."

We have also included a mock banking app view, so you can see exactly how the confusing "Available Funds" number on your phone translates to the actual cash sitting in your tank.

The two types: fixed limit vs. reducing limit

When you set up a revolving credit facility, it is crucial to know that banks treat the overarching limit differently.

1. The standard fixed limit (maximum flexibility)

With a standard facility, your overall overdraft limit stays exactly the same forever. If you have a $50,000 limit today, you will still have a $50,000 limit in ten years.

• The Benefit: This offers maximum flexibility. You have permanent access to emergency funds and total control over when you pay down the debt.
• The Danger: Because the bank isn't forcing you to pay the loan down, it is very easy to treat this like a massive, permanent credit card. If you just pay the interest every month and keep spending your principal, you will never actually clear the debt.

2. The reducing limit (forced discipline)

If you toggle the "Enable Reducing Limit" switch in the simulator above, you will see how this works. The bank slowly shrinks your total credit limit every single month, which you can see updating under Next Month's Limit.

• The Benefit: This acts as a forced savings mechanism. It ensures that the underlying debt is actually being paid off over the lifespan of the loan, protecting you from slowly draining the equity out of your house.

(Note: Every bank is different. Some banks default exclusively to reducing limits, while others only offer fixed limits).

What does your bank call it?

Every major bank in New Zealand offers a revolving credit facility, but they all wrap it in their own marketing jargon. If you are reading a bank brochure or looking at your app, here is the translation guide for what the banks actually call this product:

• ANZ: Flexible Home Loan
• ASB: Orbit Home Loan
• BNZ: Rapid Repay
• Westpac: Choices Everyday
• Kiwibank: Revolving Home Loan

Is revolving credit right for you?

Revolving credit is a financial chainsaw—an incredibly powerful tool for clearing debt quickly, but highly dangerous if you don't know how to handle it. Before asking for one, you need to understand the trade-offs.

The ultimate benefits

• Total liquidity: Your emergency fund isn't locked away in a term deposit earning a low return (which you then have to pay income tax on). It is sitting directly against your mortgage, completely tax-free, saving you thousands in interest, but fully available if the roof leaks tomorrow.
• Perfect for irregular incomes: If you are self-employed, earn seasonal bonuses, or work heavily on commission, this account acts as a financial shock absorber. You can dump massive lump sums into the account during good months without paying any "early repayment" break fees.

The serious risks

• The floating rate premium: Revolving credit accounts sit on the bank's "floating" or variable interest rate. In New Zealand, floating rates are usually noticeably higher than standard 1-year or 2-year fixed rates. If you do not keep enough spare cash flowing through the account to offset that higher interest rate, you will actually end up going backwards and paying the bank more money.
• The discipline check: This is the ultimate test. As highlighted in the simulator's dynamic summary, if you build up $10,000 of cash and then spend it on a holiday to Fiji, your debt immediately goes right back up to your maximum limit. If you lack strict budgeting discipline, you will slowly bleed cash over time.

A common strategy: The Split

Because a revolving credit facility sits on a higher floating interest rate, it is very rare for borrowers to put their entire mortgage on this type of account. The cost of having hundreds of thousands of dollars sitting on a variable rate usually outweighs the benefits.

Instead, a very common approach is to split the mortgage into multiple parts.

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