Double-entry accounting basics
What double-entry bookkeeping is, how debits and credits work, and how Qontab keeps every transaction balanced.
What double-entry accounting is
Double-entry accounting is the method of recording every transaction in two places at once: one account is debited and another is credited, for the same amount. The idea is simple — money never appears from nowhere, it always moves from one place to another, so each movement has a source and a destination. Recording both sides means your books always carry the proof of where value came from and where it went, and the two sides must agree to the cent.
It is the foundation of every serious accounting system, and the reason it has survived for five centuries is that it is self-checking: if total debits don’t equal total credits, something is wrong, and you know it immediately. Qontab is a double-entry system, so every entry it records is balanced by construction.
Debits and credits
A debit and a credit are just the two sides of an entry — left and right. They are not “in” and “out”; what they do depends on the type of account. Qontab sorts every account into one of five classes, and each class has a normal side on which its balance grows:
- Assets (cash, bank, receivables, equipment) — increased by a debit.
- Liabilities (payables, VAT payable, loans) — increased by a credit.
- Equity (owner’s capital, retained earnings) — increased by a credit.
- Revenue (sales, service income) — increased by a credit.
- Expenses (rent, salaries, professional fees) — increased by a debit.
So when you pay €100 of rent from the bank, Qontab debits the Rent expense account (expenses grow on the debit side) and credits the bank account (an asset shrinks on the credit side). One line in, one line out, equal amounts — a balanced entry. The five classes come straight from Qontab’s default chart of accounts.
The accounting equation
Everything in double-entry rests on one identity that must always hold:
Assets = Liabilities + Equity
What you own equals what you owe plus what’s truly yours. Revenue and expenses are simply equity in motion — revenue increases equity, expenses decrease it — which is why a debit-and-credit pair of equal amounts can never knock the equation out of balance. Every transaction touches the equation on both sides at once, so it stays true after each entry. The balance sheet is this equation written out at a point in time.
Why it matters
How Qontab keeps it balanced
You never hand-build debit and credit lines in Qontab. You record a plain-language transaction — an income, an expense, a transfer, a capital contribution or an opening balance — and Qontab generates the matching journal entry for you, with the correct accounts on the correct sides.
- Balanced by construction — before any entry is saved, Qontab checks that total debits equal total credits (to exact decimal precision, in your base currency) and refuses an unbalanced entry.
- Sequential numbering — each posted entry gets a gap-free number like
JE-2026-000047, so your ledger is auditable and nothing can be quietly inserted. - Edited in place — correcting a posted entry rewrites it while keeping the same number and its linked documents; Qontab does not litter your ledger with reversal entries.
The result is that the discipline of double-entry runs underneath everything you do, without you having to think in debits and credits unless you want to.
Proving the books with the trial balance
The trial balance is the report that proves double-entry held across your whole ledger. It lists every account with its balance in two columns — total debits and total credits — and the two column totals must be equal. If they are, every entry behind them balanced; if they aren’t (which can’t happen with entries posted through Qontab), you’d have a hint of where to look.
From the trial balance flow your core financial reports: the balance-sheet accounts (assets, liabilities, equity) form the balance sheet, and the income-statement accounts (revenue, expenses) form the profit & loss. One balanced ledger, every statement derived from it.
Double-entry with AI (MCP)
Connected to an AI assistant through the Qontab MCP connector, you can interrogate the books in plain language and the underlying double-entry data comes back structured. Read tools like list_transactions return the debit/credit lines of each entry, while get_trial_balance, get_profit_loss and get_balance_sheet return the proven, balanced totals — the same numbers the app shows.
Ask your assistant
FAQ
What is double-entry accounting in simple terms?
Every transaction is recorded in at least two accounts: one is debited and one is credited, for equal amounts. Money never just appears — it moves from somewhere to somewhere. Because the two sides always match, your books carry a built-in check that catches errors.
Does a debit mean money going out and a credit money coming in?
No — that is the bank's point of view, not accounting's. A debit increases assets and expenses but decreases liabilities, equity and revenue; a credit does the opposite. Whether a debit is "good" or "bad" depends entirely on the account it touches.
Do I need to understand debits and credits to use Qontab?
No. You record an income, expense or transfer in plain terms and Qontab builds the balanced debit/credit entry for you. Understanding the mechanics helps when you read reports or review an entry, but day to day the software handles the bookkeeping.