What are opening and closing balances?
Published
Definition and equation
The opening balance is an account's balance at the start of a period; the closing balance at its end:
Closing balance = Opening balance + the period's movements (signed)And the continuity rule with no exceptions: every period's closing = the next period's opening. Breaking it means a number entered or left the books from outside them.
At Al-Waha: opening bank 191,400 + the quarter's net movement (−9,000) = closing 182,400 - necessarily Q3's opening.
A distinction between account types: balance sheet accounts (bank, customers, suppliers) carry their balances forward; result accounts (revenue, expenses) close into retained earnings at year-end and start the new year at zero - revenue is a period's number, the bank is a lifetime's.
The one case where balances are "entered": migrating to a new system
Starting an accounting system mid-life, opening balances are entered at a defined cutover date:
- Choose the cutover (year-start or quarter-start - cleanest after a reconciled close).
- Enter all balance sheet balances: banks agreeing to statements, customers and suppliers by their open invoices, not one lump sum, inventory from a physical count, assets with their accumulated depreciation.
- Verify the opening balance sheet balances.
The opening balance equity trap: the unexplained difference systems park in a suspense account. Its survival after setup means balances nobody understood - explain it and zero it before the first close; never let it age.
Frequently asked questions
A brand-new business's first opening balances?
Formation balances only: deposited capital and any formation costs paid - the rest are legitimate zeros.
I found an opening-balance error months later?
A documented correcting entry in an open period adjusts the balance, with a memo - never a silent edit of the opening entry, which comparisons were built on.