Close the BooksLocks a period so a later edit cannot quietly change what was already filed or reported. Close a month at a time to stay accountant-ready and a year when you file; every lock is reversible and every unlock is recorded.
Lock the books through any date, independent of the month/year snapshots above, for closing a filed quarter, or matching a prior accountant's cut-off. No entry on or before the date can be posted or edited until you reopen.
Tip: close through the last day of a filed month/quarter/year (e.g. 12-31), QuickBooks-style. no closing entry is posted; net income rolls into Retained Earnings automatically on the Balance Sheet.