Debit
A debit is the left side of a journal entry, and it increases asset and expense accounts while decreasing liability, equity, and income accounts.
In short
Debit just means "left side" — not a withdrawal, not bad news. It grows assets and expenses: money arriving in checking is a debit, and so is a purchase hitting an expense account. On a liability, equity, or income account, a debit does the opposite — it shrinks the balance.
Also called: Dr, debit entry
Most explanations of debit reach for a mnemonic to memorize. Skip it. A debit is simply the left side of a journal entry — a directional label, the same way "north" doesn't mean "up" until you know what you're pointing at. What a debit actually does depends entirely on which account it hits.
The one rule that matters: assets and expenses grow with debits. Checking is an asset, so money arriving is a debit. Materials is an expense, so a purchase debits it. Debit a $120.50 hardware-store charge to Materials and it goes up by exactly that; debit an incoming $2,000 payment to Checking and it goes up too. In both cases the account is gaining value, and in both cases that gain is recorded as a debit, because both accounts are debit-normal.
On the other three account types — liability, equity, income — a debit does the opposite: it shrinks the balance. Paying down $300 of a credit card balance debits the Credit Card liability account, and the balance owed goes down, not up. This is the detail that trips people up: a debit isn't universally "an increase." It increases whichever accounts are debit-normal, and decreases whichever aren't.
Internally, BalanceMCP stores every debit as a positive number of cents. A $120.50 debit to Materials is stored as 12050. That convention is what makes "debits equal credits" a literal arithmetic check the database can run on every entry before accepting it — the number itself carries the sign, not a separate flag.
What people get wrong
- Assuming a debit always means a decrease, by analogy to a bank debit card withdrawal — in bookkeeping a debit increases an asset or expense account.
- Treating "debit" as inherently bad news. A debit to an expense account isn't a win or a loss on its own; it depends entirely on the account.
- Memorizing account-by-account which side is normal instead of learning the one rule (assets and expenses are debit-normal) that generates every case.
Common questions
- Why does a debit increase my checking balance but decrease my credit card balance?
- Because Checking is an asset (debit-normal) and Credit Card is a liability (credit-normal). A debit grows a debit-normal account and shrinks a credit-normal one — the same word, opposite effect, depending on the account.
- Is a debit the same as a withdrawal?
- No — that's a specific, informal use of the word from banking. In bookkeeping, a debit is a side of an entry, and whether it grows or shrinks a balance depends on the account type.
Machine-readable: /api/knowledge/concept:debit