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Debt Avalanche vs Debt Snowball: Which Works Best for New Zealanders?
If you're trying to pay off debt faster, you've probably come across two popular strategies: the debt avalanche and the debt snowball. Both work. Both will get you out of debt. But they work differently — and the right one depends on your personality as much as your maths.
What is the Debt Avalanche?
The debt avalanche means paying off your highest interest rate debt first, regardless of the balance.
You make minimum payments on everything else, then throw every extra dollar at the most expensive debt. Once that's cleared, you roll that payment into the next highest rate. And so on.
Example: You have a Gem Visa at 25.99%, a car loan at 8.95%, and a mortgage at 5.49%. The avalanche targets the Gem Visa first.
Why the avalanche works
It's mathematically optimal. You pay less total interest over the life of your debts than with any other strategy. For New Zealanders carrying credit card debt alongside a mortgage, the difference can be thousands of dollars.
What is the Debt Snowball?
The debt snowball means paying off your smallest balance first, regardless of the interest rate.
You get a quick win, which builds momentum. Once the smallest debt is cleared, you roll that repayment into the next smallest balance.
Example: Same debts as above. The snowball targets the car loan first if it has a lower balance than the Gem Visa — even though the Gem Visa costs more.
Why the snowball works
It's psychologically powerful. Research — including work by behavioural economists — shows that people who use the snowball method are more likely to stick with their repayment plan. A cleared debt feels like a win, and wins motivate behaviour change.
Avalanche vs Snowball: The NZ Context
New Zealand has some quirks that affect this decision:
Fortnightly repayments are standard here. Most NZ mortgages are repaid fortnightly, which means you make 26 repayments a year — the equivalent of 13 monthly payments instead of 12. That extra payment each year quietly accelerates your mortgage payoff, shaving years off a typical 25-30 year term. Any debt calculator you use should account for fortnightly — not monthly — repayments.
Fixed-rate mortgage terms are short. NZ mortgages typically fix for 1–3 years, then refix. This creates natural decision points where you can review your strategy, make lump sum payments, or restructure.
Student loans are interest-free for NZ-based borrowers. IRD student loans accrue no interest if you live and work in New Zealand. This means they should always sit at the bottom of your repayment priority — focus on interest-bearing debt first regardless of which strategy you choose.
Credit card rates are high. The major NZ banks charge 20–22% p.a. on credit cards. Gem Visa, Q Mastercard, and similar retail cards often charge 25–28%. Any debt at these rates should be treated as urgent.
Which Strategy Should You Choose?
| Debt Avalanche | Debt Snowball | |
|---|---|---|
| Optimises for | Total interest saved | Psychological momentum |
| Best for | Disciplined planners | People who need early wins |
| NZ student loan | Always last | Always last |
| Credit card debt | Attack first | Attack first if smallest |
Our honest take: If you have credit card debt at 20%+ alongside other loans, the avalanche almost always wins on maths. The difference in total interest paid can be significant.
But if you've tried and failed to pay off debt before, the snowball might be the strategy that finally sticks. A plan you follow is better than an optimal plan you abandon.
A Third Option: The Cashflow Strategy
There's a lesser-known third approach: prioritising the debt with the highest monthly repayment burden — regardless of rate or balance.
This is useful if cashflow is tight. Clearing a debt with a large monthly repayment frees up real money each month, giving you breathing room. Once your cashflow improves, you can switch to the avalanche to minimise total interest.
How to Calculate Your Payoff Date
To work out which strategy saves you the most, you need to know:
- Current balance on each debt
- Interest rate
- Current repayment amount and frequency
- Estimated payoff date under each scenario
Frequently Asked Questions
Is the debt avalanche better than the debt snowball?
Mathematically, yes — the avalanche saves more money in interest. But the best strategy is the one you'll actually stick to. If the snowball keeps you motivated, it may produce better real-world results for you.
Does the debt snowball actually work?
Yes. Research suggests that clearing smaller debts first creates psychological momentum that helps people stay committed to their repayment plan. Both strategies work — the difference is in motivation vs optimisation.
Should I pay off my NZ student loan first?
No. NZ student loans are interest-free for New Zealand-based borrowers, so there is no financial cost to carrying the balance. Focus on interest-bearing debt (credit cards, car loans, personal loans, mortgage) before your student loan.
What about my mortgage?
Your mortgage is likely your largest debt but often your lowest rate. Under the avalanche, it usually comes last. However, NZ mortgage refix dates create opportunities to make lump sum payments or restructure — worth reviewing each time your fixed term ends.
How do fortnightly repayments affect my debt payoff?
Significantly. Fortnightly repayments mean 26 payments per year instead of 24 monthly ones — effectively one extra month of repayments annually. Over a 25-year mortgage this can shave years off your term. Make sure any calculator you use accounts for fortnightly frequency.