Debt is not inherently bad — but the instalment culture makes it dangerously easy to pay far more than you realise for things that lose value the moment you buy them.
"Buy now, pay later." Zero-interest financing. Split it into 12 easy payments. Every checkout page now offers a way to take something home today and worry about the cost later — and on its own, that's not necessarily a problem. The trouble is that "later" rarely gets the same attention "now" does.
This lesson isn't about avoiding debt entirely. Some debt is a normal, even useful, part of building a financial life. The goal is to understand which debt is working for you, which is working against you, and exactly what an instalment plan is costing you in real numbers — not just the "$XX/month" figure on the checkout screen.
Good Debt vs Bad Debt
Good debt is used to acquire something that holds or grows in value over time — a mortgage on a home you live in, or a student loan that increases your earning power. These typically carry interest rates in the 3-8% range, and the asset or income boost they create generally outweighs the cost of borrowing.
Bad debt funds things that lose value immediately — buy-now-pay-later electronics, fashion, gadgets, or a revolving credit card balance carried month to month. These typically carry interest rates of 12-30%. The item depreciates the moment you own it, but the debt — and its interest — sticks around long after.
A simple rule of thumb: if the interest rate on a debt is above roughly 10%, paying it down should be a financial priority — ahead of most other goals except a starter emergency fund.
| Debt Type | Examples | Typical Rate | Classification |
|---|---|---|---|
| Mortgage / home loan | Buying a home you will live in | 3–7% | ✅ Potentially good |
| Student / education loan | Degree that increases earning power | 4–8% | ✅ Potentially good |
| Auto loan (necessary vehicle) | Car required for work | 6–12% | ⚠️ Neutral — minimise term |
| Buy now, pay later (BNPL) | Electronics, clothing, lifestyle | 0–36% (varies) | ❌ Usually bad |
| Credit card (revolving balance) | Unpaid monthly balance | 18–30% | ❌ Bad — pay off immediately |
| Personal loan (lifestyle) | Holiday, wedding, gadgets | 12–28% | ❌ Bad — avoid or clear fast |
Many retailers and credit card companies offer 0% interest for an introductory period. These can be genuinely useful if you pay off the full balance before the promotional period ends.
The trap: if even one payment is missed, or the balance isn't cleared in time, interest often applies retroactively to the full original amount. Use 0% offers with a clear payoff plan and calendar reminders — never to buy something you couldn't otherwise afford.
Avalanche vs Snowball: Which Order to Pay Off Debt
If you're carrying more than one debt, the order you pay them off in matters. There are two common approaches:
- Avalanche method — pay off the debt with the highest interest rate first, while making minimum payments on the rest. This is mathematically optimal and saves you the most money overall.
- Snowball method — pay off the smallest balance first, regardless of interest rate, then roll that payment into the next-smallest. This costs more in total interest, but the quick wins can build momentum.
| Avalanche Method | Snowball Method | |
|---|---|---|
| How it works | Pay minimums on all debts. Put extra money toward the highest interest rate debt first. | Pay minimums on all debts. Put extra money toward the smallest balance first. |
| Best for | People who are motivated by math and total savings | People who need early wins to stay motivated |
| Total interest paid | Lower — saves more money overall | Higher — costs more in the long run |
| Psychological impact | Slower early progress — requires discipline | Quick wins build momentum — easier to sustain |
| Verdict | Mathematically optimal | Behaviourally effective |
If you're motivated by numbers, avalanche is the better choice. If you've started and abandoned debt payoff plans before, snowball's early wins might be what keeps you going — and the method you actually stick to beats the "optimal" one you give up on after two months.
The Real Cost of Instalments and EMI
Here's the part that "$XX/month" hides: the total you'll actually pay is the monthly payment multiplied by the number of months — and once interest is included, that total is almost always higher than the cash price. The longer the term and the higher the rate, the larger the gap between the price tag and what you actually pay:
| Item | Purchase Price | Interest Rate | Repayment Term | Total Paid | Extra Cost |
|---|---|---|---|---|---|
| Smartphone | $800 | 18% | 24 months | $1,008 | +$208 |
| Laptop | $1,200 | 22% | 36 months | $1,716 | +$516 |
| Holiday trip | $2,500 | 20% | 24 months | $3,112 | +$612 |
| Used car | $8,000 | 12% | 48 months | $10,032 | +$2,032 |
* Approximate figures based on simple interest calculations. Actual amounts vary by lender and compounding method.
When you see a monthly payment offer, always calculate the total cost first. Multiply the monthly amount by the number of months, then compare that to the cash price.
If the total is significantly higher, ask: is this purchase worth the premium I'm paying for the convenience of not having the money now? Often the honest answer is no — or not yet. Saving up first and buying outright is almost always the cheaper path.
Use the calculator below with the actual numbers from an instalment plan you're considering (or already paying), and see what it really costs.
Enter the cash price, interest rate, and term of an instalment plan or loan to see your monthly payment, total cost, and how much more you'll pay than the sticker price.
Building Your Debt List
Before you can apply either strategy, you need a complete picture of what you owe. Most people are carrying more debt than they consciously track because individual monthly payments feel small.
Your action step builds this list. For each debt, you need four numbers: the current balance, the interest rate, the minimum monthly payment, and the remaining term. With those four numbers, you can calculate your payoff timeline and total cost for each debt — and then decide where to direct extra payments.
A common mistake is splitting extra payments across multiple debts. Putting an extra $50 toward three different debts has almost no impact on any of them.
Concentrate all extra payments on one target debt — whichever your chosen strategy dictates — while paying minimums on everything else. Once that debt is cleared, redirect its entire payment amount toward the next target. This creates compounding momentum.
How Much of Your Income Should Go to Debt?
A useful rule of thumb: total monthly debt repayments — excluding your mortgage — shouldn't exceed about 15% of your take-home income. Minimum payments belong in your Needs bucket from the 50/30/20 framework in Lesson 2; any extra you put toward debt above the minimum belongs in your Future bucket, accelerating your path to being debt-free.
If your current debt payments already exceed that 15%, it doesn't mean you've failed — it means debt reduction is your top Future-bucket priority for now, ahead of other savings goals (aside from a small starter emergency fund).
Complete this before moving to Lesson 5.
- List every debt you currently carry: credit cards, personal loans, auto loans, student loans, buy-now-pay-later balances, anything with a repayment obligation.
- For each debt, record: current balance, interest rate, minimum monthly payment, and remaining term.
- Calculate the total amount you currently owe across all debts.
- Identify your highest interest rate debt (Avalanche target) and your smallest balance debt (Snowball target).
- Decide which strategy suits you and write down the order in which you will pay your debts off.
List every debt with its balance, rate, and minimum payment, then follow your Avalanche or Snowball payoff order month by month.
