Journal Entry
A journal entry is a dated record with a memo and two or more lines, each naming an account and an amount, where the amounts always net to exactly zero.
In short
The basic unit of bookkeeping: a date, a short memo, and lines that name an account and an amount each. A $120.50 hardware-store charge is one entry with two lines — Materials debited, Checking credited. Once posted, an entry is permanent; it can only be undone by a reversing entry, never edited.
Also called: journal posting, ledger entry
A journal entry is the atomic record in double-entry bookkeeping: a date, a memo, and two or more lines that each name an account and an amount, with the amounts summing to exactly zero. It is the only way anything enters the ledger.
Netting to zero is the definition rather than a validation rule attached to it. An entry whose lines do not cancel is not an invalid entry, it is not an entry — which is why a system that enforces this can enforce it absolutely, and why the constraint lives in the database here rather than in code that could be bypassed.
Two or more lines, not exactly two. One charge split between several accounts is a single entry with several debit lines and one credit line, and it is still one event with one date and one memo. Splitting it into separate entries would misrepresent what happened.
Amounts are whole cents, and a fractional cent is rejected rather than rounded. Most entries are created as a side effect of categorizing a bank transaction, where one side is already known; entries posted directly, with no bank transaction behind them, are the exception rather than the rule.
What people get wrong
- Entering an amount as a dollar decimal (12.50) instead of whole cents (1250) — a fractional cent is rejected, not rounded.
- Expecting to edit a posted entry directly. Nothing in BalanceMCP allows that; the fix is always a reversing entry followed, if needed, by a correct one.
- Assuming a bank transaction and a journal entry are the same thing — a transaction is a raw fact; categorizing it is what turns it into an actual entry.
Common questions
- Can one journal entry have more than two lines?
- Yes — a single charge can split across several accounts as long as the whole entry still nets to zero, such as one payment split between an expense and a sales-tax liability.
- What happens if the lines don't balance?
- The entry is rejected outright, not partially accepted, and the error states exactly how far off it was and in which direction.
Machine-readable: /api/knowledge/concept:journal-entry