Money 101 · Module 3 of 6: Debt · Lesson 4 of 4 · 4 min read
Pay off debt or invest?
You have some money left each month. Should it go on your debt or into investments? The answer starts with one idea: paying off debt is a return you can count on.
Paying off debt is a certain return
Every euro you pay off a debt stops costing you its interest rate. Pay off €1,000 on a card at 18% and you avoid roughly 1,000 × 0.18 = €180 of interest over a year. That is an 18% return, with no risk.
Investing has no such promise. Markets go up and down, and some years are negative. To come out ahead, your investments must earn more than the debt's rate on average, after fees, over the whole period.
Tax raises the bar
Interest you avoid by paying off debt is not taxed. Investment gains often are, depending on your country (see the country rules). So with tax, investing needs to earn even more than the debt's rate just to break even.
For expensive debt such as cards and overdrafts, that is a high bar to clear year after year. For cheap debt, such as many mortgages, investing at the same time can make sense if you can live with the risk.
Sort these out first
Before you compare the two, check these points:
A starter cushion. Without any savings, the next surprise lands back on the card. A small buffer comes first – see how big your emergency fund should be.
Employer pension matches. If your employer adds money when you pay into a pension, that match can be worth more than paying off even expensive debt. How this works depends on your country.
Every minimum payment. Both choices keep paying all minimums on time. Missing them adds fees.
Early-repayment fees. Some loans charge for paying early, which lowers the benefit of overpaying.
Try it with numbers
Say you owe €3,000 on a card at 18%, pay a €90 minimum and have €150 extra each month. Paying off the card "earns" 18% for certain. An investment you expect to return 7% a year would need to beat 18% to win – and more than that once tax on gains is counted.
The pay off debt or invest calculator runs both plans with the same money each month and shows the break-even return: the yearly return at which both plans end level. If you have several debts, start with the most expensive one, or plan the order with avalanche vs snowball.
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Key takeaways
Paying off debt earns its interest rate, guaranteed.
Investing must beat that rate after fees and tax to win.
Keep a starter cushion and take any employer match first.
Try it
Opens the calculator with a €3,000 card at 18%, a €90 minimum, €150 extra a month and a 7% expected return over 5 years.
4 questions. Pick an answer to see why it's right or wrong.
Paying off a card that charges 18% a year is like earning what?
Not quite. The money stops future interest, which is a real saving.
Right. Each euro paid off stops costing 18% a year, with no market risk.
Not quite. Paying off debt doesn't depend on markets.
Show the answer
A certain 18% return – That is an 18% return, with no risk.
Why does tax on investment gains matter in this choice?
Not quite. Tax lowers what investing actually leaves you with.
Not quite. Interest you avoid by paying off debt is not taxed.
Right. Avoided interest isn't taxed, but investment gains often are.
Show the answer
It raises the return investing needs just to break even – So with tax, investing needs to earn even more than the debt's rate just to break even.
What should usually be in place before you overpay debt or invest?
Not quite. With no savings at all, a surprise bill turns into new debt.
Right. Without it, the next surprise goes back on the card.
Not quite. That adds borrowing rather than a buffer.
Show the answer
A small starter cushion of savings – Without any savings, the next surprise lands back on the card.
Your employer adds money when you pay into a pension. How can that change the answer?
Not quite. Every minimum payment still has to be made on time.
Right. Money your employer adds on top of your own payment is money you would otherwise miss out on.
Not quite. A match can change which choice comes out ahead.
Show the answer
The match can be worth more than paying off even expensive debt – If your employer adds money when you pay into a pension, that match can be worth more than paying off even expensive debt.
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Education, not advice. I'm not a financial adviser and I don't know your situation. These tools show the maths behind common rules of thumb; check important decisions with a qualified professional. Full disclaimer.
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