Why the card seems sensible

Before I argue with the card, I want to be fair to it, because there's nothing foolish in how you've been using it and a great deal of design.

It smooths the month. Money comes in on one day and goes out on thirty, and the card lets the thirty happen before the one. Without it the last week of the month would be thin.

It's for emergencies. The boiler. The car. The thing you can't predict. A card is what stands between you and a bad week becoming a disaster.

The points. The cashback. Using the card for everything and paying it off means a free flight, or a few quid back, and only a fool leaves that on the table.

It's normal. Nearly everyone you know has a balance. A card with nothing on it is the odd one.

The bank gave you the limit. Somebody with a spreadsheet decided you could handle five thousand. They know what they're doing, and they're not going to lend you money you can't afford.

The interest is small. A few pounds a month, on a statement you don't open. It's the cost of the convenience and it's not much.

And you always pay something. Never missed a payment. Never over the limit. That's a responsible person, and a book that suggests otherwise is being unfair.

There are needs under all of this. To get through the month without a thin week. To be covered if something breaks. Not to leave free money on the table. To be a responsible adult with a card like everyone else. Those are real, and the method later in the book meets them without the balance. What I'll show is that the card meets them by lending you the thing you needed at a price you've arranged not to see, that the smoothing has become a level you live at rather than a bridge you cross, and that the responsible person paying the minimum on time is the regulator's picture of someone in trouble.

It's the way you've always done it, too. The card arrived at eighteen or twenty-two with a limit that felt like a compliment, and the habit of running a little way up it was formed before you'd ever seen a statement, and a habit formed then isn't a decision now. It's how money has worked for as long as you've had any.

One thing before I start. If you use a card and clear it in full every month, this book isn't about you. You're using the card the way the design pretends everyone does. The book is about the balance that doesn't go away, and if yours does, keep doing what you're doing and lend this to someone.