Why double-entry?
The 500-year-old idea at the heart of every set of books.
Double-entry bookkeeping is the standard way to track money. It's also the only way that catches mistakes automatically. This page explains why.
The single-entry world
Imagine tracking your business in a spreadsheet:
| Date | What happened | Amount |
|---|---|---|
| 2026-05-01 | Web design for Acme | +$1,200 |
| 2026-05-02 | Software subscription | -$55 |
| 2026-05-03 | Coffee | -$8 |
This is single-entry. It works for a personal expense tracker. It fails for a business because:
- It doesn't capture where money came from / went to. That $1,200 — was it cash or a credit-card sale? That $55 — credit card or bank?
- Nothing balances. No way to know if you forgot to record something.
- No balance sheet. You can compute net change but not what you own or owe.
The double-entry world
In double-entry, every transaction has two sides:
- One account gets a debit (the destination of value).
- One account gets a credit (the source of value).
The two sides always equal each other. So that $1,200 sale becomes:
| Account | Debit | Credit |
|---|---|---|
| Checking Account | $1,200 | — |
| Service Revenue | — | $1,200 |
Translation: "$1,200 went into Checking; the source was earning revenue." Both true. Both captured.
Why force this?
Three reasons:
1. Catches mistakes. If debits don't equal credits, the books are broken and you know it. Single-entry never tells you when you've made an error.
2. The fundamental equation always holds.
Assets = Liabilities + Equity
Every dollar in an asset can be traced back to either someone's investment (equity), someone's loan (liability), or accumulated profit (also equity). The books "balance" because of double-entry — every line debits exactly what another line credits.
3. Better answers. With double-entry you can ask:
- "How much did we spend on software last quarter?" (sum debits to software expense)
- "Who do we owe?" (look at liability accounts)
- "What's our cash position?" (one number, instantly correct)
These questions are hard or impossible in single-entry.
Where it came from
A Franciscan friar named Luca Pacioli wrote it down in 1494 in Venice. He didn't invent it — Italian merchants had been doing it for two centuries already. He just documented it. The system has barely changed since. Five hundred years and counting.
Every accounting standard (US GAAP, IFRS, you name it), every audit, every financial statement of every public company on earth — all built on double-entry. It works.
In Axerity
Every transaction is enforced to balance at the database level. Lines that don't sum to zero are rejected before they ever hit your books. This isn't a UI hint — it's a guarantee.