Your expense tracker knows you spent LKR 4,500 at the supermarket. Ask it what you are worth and it has nothing to say — because recording that money left tells you nothing about what you own or what you owe.
That gap is the whole reason double-entry exists. The idea is not intimidating: every transaction touches two accounts instead of one. It was written down by the Venetian friar Luca Pacioli in 1494, and it is still the only method that produces a balance sheet you can trust rather than a list of transactions you can scroll.
Every rupee, twice
Spend LKR 4,500 on groceries from your card, and two things happened, not one: your groceries expense went up by 4,500, and your card balance went up by 4,500 too (you owe more). One entry, two sides: a debit and a credit that always balance to zero.
That "always balances" part is the whole point. It's not a rule imposed for accountants' convenience; it falls directly out of what a transaction is. Money doesn't appear or disappear; it moves from one place to another, or an obligation is created alongside an expense. Recording only one side of that movement would mean recording half of what actually happened.
The five account types, and which way they move
Every account in a ledger is one of five types, and each has a "normal" direction it grows in:
| Account type | Grows with | Example |
|---|---|---|
| Assets | Debit | Bank balance, cash, receivables |
| Liabilities | Credit | Credit card balance, loans owed |
| Equity | Credit | Owner's capital, retained earnings |
| Income | Credit | Salary received, freelance invoice paid |
| Expenses | Debit | Groceries, rent, utilities |
You don't need to memorize which side is which to use Salli, but this table is why the groceries example above works the way it does: an expense (groceries) debits, and a liability (card balance owed) credits. Same transaction, opposite-direction entries, net effect zero.
A worked example: getting paid and paying rent
Take a simple month. You're paid a LKR 200,000 salary into your bank account, then you pay LKR 45,000 in rent from that same account.
| Entry | Account | Debit | Credit |
|---|---|---|---|
| Salary received | Bank (asset) | LKR 200,000 | |
| Salary received | Salary income | LKR 200,000 | |
| Rent paid | Rent expense | LKR 45,000 | |
| Rent paid | Bank (asset) | LKR 45,000 |
Notice the bank account appears twice: once as a debit (money arriving) and once as a credit (money leaving), and each of the two transactions balances on its own. Add up every debit column and every credit column across your whole ledger, for any period, and they must be exactly equal. If they're not, something was recorded wrong, and you know it immediately rather than discovering it months later when a report doesn't add up.
Why this matters more than it sounds
Because both sides must always balance, an error (or an attempt to quietly alter a number) shows up immediately as an imbalance. A single-entry system (just a list of "money in" and "money out," like a simple spreadsheet) has no such check: delete a row, mistype a figure, and nothing else in the system notices. Double-entry catches that class of mistake structurally, not by asking you to be careful.
It's the same discipline that's kept real accounting honest for centuries. Salli just automates the bookkeeping so you never have to think about which side is which, and you get the trustworthiness of proper double-entry books without needing to be a bookkeeper yourself.
What it means for you
You never have to understand debits and credits to use Salli day-to-day. Type "spent 4,500 on groceries" and the correct double-entry gets drafted for you: the right accounts, the right sides, balanced automatically. But the rigor underneath is exactly why the numbers you see (your net worth, your tax position, your spending by category) are ones you can trust. When a number in Salli looks wrong, the first question is never "did the math break" (double-entry structurally prevents that); it's "was this transaction categorized the way I meant."
Double-entry mechanics are a well-established accounting standard, not something that varies by jurisdiction, so the account types and balancing rule above apply the same way whether you're tracking rupees, dollars, or any other currency.
Where this leaves you
Double-entry is not an accounting aesthetic. It is the only reason a piece of software can tell you what you are worth instead of merely what you spent.
Salli is built on one: every figure — your net worth, your tax position, your Freedom date — traces back to posted, immutable entries you can inspect. Corrections are made with reversing entries, never by editing history, which is what makes a number from last year still true this year.
