What is a period lock?

Definition

A period lock is the system setting that closes a month so no further entries can be posted to it. On the books, this is a switch in the software, not an account you debit or credit.

Once June is locked, a journal entry dated June 30 will be rejected. New work has to land in July or in a later open month.

A bookkeeper who locks June after statements go out is protecting those numbers. A late invoice that arrives the next week posts to July instead of slipping back into June.

Where it shows up

Balance Sheet: Related to stopping later postings into a closed month.

P&L: Related to stopping later postings into a closed month.

Cash flow: Related to stopping later postings into a closed month.

See also: Month-End Close · Posting · Accounting Period

When you look at your Balance Sheet, a lock does not print as a line. It is why June's balances stop changing after statements go out.

When you look at your Income Statement, the same protection applies. June revenue and expense stay as issued, because later posting cannot reopen that month.

On the Statement of Cash Flows, June cash figures stay put for the same reason. A July payment does not rewrite the June statement.

You will not find "period lock" on the statements. You will find it in the accounting system's period settings, often as a closed or locked flag next to June.

The general ledger still holds every June entry that posted before the lock. It simply will not accept a new one dated inside the closed month.

How it works

Someone with rights in the system marks June closed. After that click, the software refuses postings whose date falls in June.

Users still work in July. Bills, deposits, and payroll dated July 1 and later post as usual.

A late June invoice that arrives after the lock cannot be dated June 30. The bookkeeper dates it July, or an admin with reopen rights opens June again, posts, and locks it again.

Reopening is a controlled exception. Internal controls usually limit who can reopen a month, and the audit trail records the reopen, the extra posting, and the second lock.

Do not lock June while adjusting journal entry work is still underway. The lock comes after the numbers are the ones you are willing to issue.

Do not treat the lock as the close itself. The close is the work of finishing June; the lock is the switch that stops later changes.

A lock can be set by month, by module, or by the whole company file. Soft locks warn; hard locks block the posting.

Example

A bookkeeper finishes June statements on July 5 and locks June that afternoon. The Financial Statement Package has already gone to the owner.

On July 8 a vendor emails a June vendor bill for $900 of parts. The bookkeeper tries to date it June 30, and the system refuses the posting.

The bill posts to July instead. June's issued statements do not change.

If the $900 truly belongs in June and the owner agrees to reissue, an admin can reopen June, post the bill, and lock the month again. That path is the exception, not the daily habit.

Most late paperwork after a lock stays in the open month. The lock is doing its job when the July date is the one that takes.

Common mix-ups

A period lock is not the month-end close. The close is the routine of finishing the books so statements can be issued; the lock is the system switch used after that work is done.

A period lock is not cutoff. Cutoff is the timing rule that says which month an event belongs to; the lock only stops later postings into a month already closed.

A period lock is not a close checklist. The checklist is the task list; the lock is one switch at the end, not the list itself.

Related terms

• Month-End Close: The monthly version of the close, ending in issued financial statements.
• Posting: Recording a journal entry into the general ledger accounts.
• Accounting Period: The span of time a set of financial statements covers.
• Close Checklist: The task-by-task list of everything that must be done to close a period.
• Audit Trail: The traceable chain from a reported number back to its source document.
• Internal Controls: The procedures that keep the books accurate and assets protected.
• Adjusting Journal Entry: An entry made at period end to record accruals, deferrals, and corrections.
• Cutoff: The rule that transactions land in the period in which they actually occurred.