There are two words that make people run away faster than any others, when money comes up.
Debit. And Credit.
They sound like a failed exam. Like a sheet from an accountant you don't feel like reading. Like a column of red numbers and a column of black ones, and you never knowing which side you're on.
I want to take that fear away from you now, in a few lines.
Because Debit and Credit don't mean right and wrong. They don't mean you're owed money or you owe it. They don't mean anything good or bad.
They're just two labels. Two sides of the same thing.
And to explain them I won't use a corporate balance sheet. I'll use a piggy bank.
The piggy bank on the nightstand
Let's take the simplest example in the world.
You have 50 euros in your wallet. At the end of the day you take a 20 note and put it in the piggy bank on the nightstand, the one where you set aside spare cash for the summer trip.
How much money do you have now, in total?
Still 50 euros. Nothing has changed in your wealth. You've only moved 20 euros from one pocket to another.
But one precise thing has happened: those 20 euros left one place and arrived in another.
They went out of the wallet. They went into the piggy bank.
There. You've just made, without knowing it, a double-entry record.
Double-entry is an accounting technique more than five centuries old — the first organized description dates to 1494 — and this is all of it, in principle: every time money moves, writing it down once is not enough. You write it down twice. Where it left from, and where it arrived.
On one side you note that the wallet has 20 euros less.
On the other you note that the piggy bank has 20 euros more.
Two notes. Same movement. Seen from two sides.
And here come Debit and Credit
Those two notes have a technical name.
The side where the money arrives and the side the money leaves from are called, in the accounting tradition, Debit and Credit.
And now comes the part I want to stay with you.
Debit and Credit are not a judgment on the movement. There's no "good" side and no "bad" side. There's no side where you're right and no side where you're wrong.
They're simply the conventional names of the two sides of every entry. Like saying "left" and "right", or "above" and "below". Labels of position, not grades.
So much so that the everyday meanings don't help you at all: "Credit" here doesn't mean "someone owes you money", and "Debit" doesn't mean "you're in debt". Each one means only: this is the side of this particular entry.
I know that, read like this, it sounds like a technicality. But it's the exact point where almost everyone gets stuck: they try to translate "Debit" and "Credit" with their everyday meanings, and they get lost. In accounting those two words have a technical meaning all their own. Accept it once and you'll never fear them again.
Like "left" and "right" on a boat: on land they're just two directions, at sea they become port and starboard and name two precise sides of the hull. A common word that, in a trade, takes on a precise meaning.
So, back to the piggy bank:
The piggy bank that receives the 20 euros goes on one side.
The wallet that gives them up goes on the other.
Which of the two is called Debit and which Credit depends on the type of account and on a precise accounting rule — and this is something that, truly, you don't have to memorize. Further down I'll tell you why.
Why twice and not once
At this point the right question is: why on earth would I write everything down twice? Wasn't it easier to note "20 euros in the piggy bank" and be done?
Easier, yes. But more fragile.
Because writing it twice has an almost magical consequence, and it's the real reason serious companies have done it for six hundred years.
If every movement always has two sides that match — 20 euros out here, 20 euros in there — then, adding up everything that went out and everything that came in across your entire book, you must get the exact same number.
If it matches, everything is in order.
If it doesn't, you've made a mistake somewhere — and you know it immediately, without having to re-check from memory month by month.
This equilibrium has a name: it's called balancing. It's double-entry's safety net. It's the thing that, in an app that only records a list of expenses, simply doesn't exist.
Let me give an example so you can feel the difference.
Marco uses an app that only records outflows. One month he forgets to record an 80-euro charge. The app doesn't protest: it was a list, it became a shorter list. The mistake vanishes and nobody ever notices.
In double-entry that charge has two sides. If you record only one, the books no longer balance. And that small imbalance is a light switching on: something is missing here.
Balancing is the reason a picture of your wealth built this way is a true picture, and not an optimistic estimate. It lets nothing fall through — not even the €5.20 coffee, not even the 80-euro charge that had slipped your mind.
The fear of the wrong column
Let's go back for a moment to the initial fear, because I want to close it for good.
Most people who got burned by accounting got burned on one thing only: the terror of putting an amount "in the wrong column".
Debit or Credit? What if I get the side wrong?
It's a legitimate worry, if you have to keep books by hand in a paper ledger. There, a wrong side is a real error, to be hunted down and corrected.
But it's exactly the piece of drudgery that makes no sense to unload onto you in 2026.
Deciding on which side — Debit or Credit — each half of a movement lands is a mechanical rule, always identical to itself. It's the kind of thing a computer does perfectly and without ever slipping. You only have to say what actually happened — 20 euros left the wallet and went into the piggy bank — and the correct placement on the two sides is computed underneath.
In Cashfulness the accounting engine is double-entry for exactly this reason: every movement you record is written on its two sides, and those two sides balance on their own. What's left to you is the human part — what happened — not the bookkeeper's part — which column do I write it in.
And there's a second helping hand, even gentler for those starting from zero.
You're not forced to use those words right away
One thing I cared about, building Cashfulness, was this: the real terms must all be there, but nobody should feel shut out for not knowing them yet.
So whoever is starting out, and still feels a little intimidated by "Debit" and "Credit", can reason in everyday words — money in, money out, and that reassuring everything adds up when the books balance.
The technical terms — Debit, Credit, balancing — remain underneath, always, because they're the engine. But you meet them explained, at the right moment, without having them dumped on you all at once on day one.
Because this is my underlying conviction, and I repeat it often: simplicity doesn't mean removing substance.
The fashionable "simple" apps get their simplicity by throwing pieces away — the small expenses, the awkward movements, the subtleties. They give you a clean picture because it's an incomplete picture.
Double-entry does the opposite: it keeps everything in, and takes away only the drudgery of managing it by hand. The substance stays whole. It's the bookkeeper's work that disappears.
One full loop, to make it stick
Let's run the movement again from the start, now that the words no longer scare.
You have 50 euros in your wallet.
You move 20 euros into the piggy bank.
Where the money comes from: the wallet, which now has 20 less.
Where the money goes: the piggy bank, which now has 20 more.
Two sides. One single truth: your total money is still 50, but now you know exactly where it is.
And if tomorrow you take those 20 euros from the piggy bank and buy fuel with them, the loop repeats: 20 leave the piggy bank, 20 go off into "transport". Where it comes from, where it goes. Always two sides.
Do this for every movement in your financial life — the salary coming in, the rent going out, the transfer you move, the investment you make — and in the end you have something most people have never had: a picture that balances, where nothing is missing and nothing is doubled by mistake.
From that picture comes your true position — what everything you own is worth, minus everything you owe. The coordinate you start from for every decision. (I've written about it at length here.)
But that's another story, and today one thing was enough for me.
Taking away your fear of two words.
Debit and Credit are not a judgment. They're just where it comes from and where it goes. I learned them with a piggy bank when I was a boy, and they've never scared me since.
I hope that from now on they won't scare you either.
— Vittorio