Paying off a card at 20% is a sure 20% return. Nothing in the market promises that.
Clear expensive debt first.
You owe €12,000 on a card at 20% a year. You have €1,000 a month: ten chips.
Paying off a 20% debt is a sure 20% return.
← Red LinesRed Line 21 of 48 The idea The numbers How people do it Where it bends This game’s numbersHow strong the proof is Where it comes from
Every euro of expensive debt you pay off stops costing its interest, every year, for sure. No investment can promise that.
€1,000 off a card at 20% saves €200 a year. The same €1,000 invested might make about €70 in a good year, and might lose.
List debts by rate, highest first. Pay the minimum on all of them, and everything spare on the top one. Then the next.
Cheap, long debt can sit while you invest.
Worked out on this page
=Outside the four steps: it follows from the arithmetic
True by the sumsPaying off debt at 20% saves 20% a year for sure, which no investment promises. That is arithmetic; the data show many people miss it.
- Self-control, financial literacy & the co-holding puzzle John Gathergood & Jörg Weber, Journal of Economic Behavior & Organization 107, 455-469, 2014
Checked 2 Nov 2026 · How we grade
- A Strong proof: Many good studies or long official data, from different teams or countries, point the same way.
- B Good proof, with limits: Solid studies agree on the direction, but the size varies, or the data covers few places or few kinds of people.
- C Mixed proof: Some good studies for, some against, or the evidence covers only part of the line.
- D Thin proof: Mostly one book’s argument, one survey or stories. It may be wise, but it has not been tested well.
- = True by the sums: It follows from arithmetic, so no study can overturn it. We still show what real data says.
George S. Clason, The Richest Man in Babylon (1926). In our words, not quoted.
See it in numbers: Debt (From Zero)
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