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Which Debt Repayment Strategy Is Right for Me? A Practical NZ Guide
You know you want to pay off debt faster. But which strategy actually gets you there — and which one is right for your situation? There's no single correct answer. The best strategy depends on your interest rates, your balances, your cashflow, and honestly, your personality. This guide walks through a real NZ example using all three strategies so you can see exactly how the numbers play out — including one result that surprises most people.
The Three Strategies
There are three main approaches to debt repayment:
The Avalanche (Money Saver) — pay off your highest interest rate debt first. Mathematically optimal — saves the most in total interest.
The Snowball (Motivator) — pay off your smallest balance first. Psychologically powerful — builds momentum through quick wins.
The Cashflow Booster — pay off your highest monthly repayment first. Designed to free up cashflow fastest — but only works as intended in specific situations (more on that below).
Want a deeper explanation of avalanche vs snowball? Read our full comparison guide →
Meet Sam — A Typical NZ Borrower
Sam has four debts and $200 extra per fortnight to put toward repayments.
| Debt | Balance | Rate | Monthly |
|---|---|---|---|
| Gem Visa credit card | $3,500 | 25.99% | $105 |
| Personal loan | $8,000 | 13.50% | $220 |
| Car loan | $12,000 | 9.95% | $380 |
| Mortgage | $320,000 | 5.49% | $1,800 |
Total debt: $343,500 · Monthly repayments: $2,505 · Without any strategy: debt-free December 2056
Strategy 1 — The Avalanche
Sam targets the Gem Visa first (25.99% — highest rate), then the personal loan (13.50%), then the car loan (9.95%), then the mortgage (5.49%).
The avalanche clears the expensive debt fast. By December 2026 the Gem Visa is gone — and every dollar that was going to that 25.99% debt rolls into the next loan.
Strategy 2 — The Snowball
Sam targets the Gem Visa first (smallest balance at $3,500), then the personal loan ($8,000), then the car loan ($12,000), then the mortgage.
Wait — the results are identical to the avalanche. Why? Because in Sam's case, the smallest balance (Gem Visa at $3,500) also has the highest interest rate (25.99%). Both strategies agree on which debt to target first. When that happens, avalanche and snowball produce exactly the same outcome.
This is worth knowing: the two strategies only diverge when your smallest balance isn't your highest rate debt. If you have a $500 store card at 12% alongside a $5,000 personal loan at 18%, the snowball targets the store card first while the avalanche targets the personal loan — and the results will differ.
Strategy 3 — The Cashflow Booster
Sam targets the mortgage first (highest monthly repayment at $1,800), then the car loan ($380), then the personal loan ($220), then the Gem Visa ($105).
The cashflow booster costs Sam $6,575 more in interest than the avalanche — and takes two months longer to become debt-free. But the bigger problem is that it doesn't even deliver its core promise: the mortgage takes until 2040 to clear, so Sam waits 14 years before getting any cashflow relief. Meanwhile, the Gem Visa at 25.99% runs all the way to 2031 — racking up interest the entire time.
So When Does the Cashflow Booster Actually Work?
The cashflow booster works when your highest repayment loan can be cleared quickly — not when it's a 25-year mortgage. Imagine Sam had a different situation: a $15,000 car loan at $850/month that could be cleared in 18 months. Targeting that first would free up $850/month relatively quickly, giving real breathing room to redirect toward other debts. That's the cashflow booster working as intended.
The lesson: before choosing the cashflow booster, ask yourself how long it will actually take to clear that top repayment loan. If the answer is years rather than months, the strategy loses its main advantage.
Which Strategy Should Sam Choose?
| Avalanche | Snowball | Cashflow Booster | |
|---|---|---|---|
| Debt-free date | May 2040 | May 2040 | Jul 2040 |
| Interest saved | $196,361 | $196,361 | $189,786 |
| First debt cleared | Dec 2026 | Dec 2026 | Jul 2040 |
| Best for | Minimising interest | Motivation | Quick cashflow relief* |
*Only when the highest repayment loan can be cleared in months, not years.
For Sam, avalanche and snowball are equally optimal. The cashflow booster costs more and takes longer — because the highest repayment loan is also the longest to clear.
How to Choose Your Strategy
Choose Avalanche if: You're carrying high-rate debt (20%+) and want to minimise total interest. Mathematically it's almost always the best choice when credit card debt is involved.
Choose Snowball if: You've tried paying off debt before and struggled to stay motivated. The quick wins of clearing small balances keep you committed — and a plan you follow beats an optimal plan you abandon.
Choose Cashflow Booster if: Your budget is genuinely tight right now and you have a large-repayment loan you can clear within 12–18 months. The freed-up cashflow gives you real breathing room. If your highest repayment loan will take years to clear, choose a different strategy.
Frequently Asked Questions
Is the debt avalanche always the best strategy in NZ?
Mathematically, yes — the avalanche minimises total interest paid. But it's only the best strategy if you stick to it. If you've struggled with motivation before, the snowball's quick wins may produce better real-world results even though it costs slightly more in interest.
When does the cashflow booster method make sense?
The cashflow booster works best when your highest repayment loan can be cleared within 12–18 months. For example, a $15,000 car loan at $850/month could be cleared relatively quickly, freeing up real cashflow. If your highest repayment is a mortgage that takes years to clear, the cashflow booster loses its main advantage and costs more in interest.
What happens when my avalanche and snowball results are identical?
This happens when your smallest balance loan also has your highest interest rate — both strategies agree on which debt to target first, so the outcomes are the same. The strategies only diverge when your smallest balance and highest rate belong to different loans.
How does rollover work in a debt repayment strategy?
When a loan is fully paid off, its repayment amount rolls into the next priority loan automatically. This compounding effect — sometimes called a debt snowball or avalanche roll — is what makes structured repayment strategies so powerful. You're not spending more money, just redirecting payments that already exist.
Should I pay off my NZ student loan or other debt first?
Your NZ student loan is interest-free if you live and work in New Zealand, so it should always sit at the bottom of your repayment priority. Focus on interest-bearing debt — credit cards, personal loans, car loans, mortgage — before making extra student loan payments.