Playbook: last month's numbers changed after the books were closed

The situation

The books for June were closed on 2 August. Two weeks later a supplier bill dated 28 June arrives, and someone posts it as it is. June's results change, the VAT return already filed for the quarter no longer matches the ledger, and nobody can say which number the auditor saw.

Closing a period is how you say *these numbers are final*. Otiox enforces it: nothing can be posted into a closed or locked month, and reopening one is a visible, deliberate act.

Before you start

• Periods are calendar months. New Period adds any that are missing.
• Closing needs the accounting permission; reopening a closed period is an admin action.

Step 1 — Close and lock the period

Open Accounting → Settings → Periods.

What you see: one row per month with its status (Open, Closed or Locked), who closed it and when, notes, and the actions available.

• In the demo, January to June 2026 are closed. June was closed by a named user on 2 August 2026; the earlier months by the system at month end.
• July to December are still open, each with Close Period.
• The banner at the top says it plainly: *posting transactions to closed or locked periods is not allowed.*

When you close a month: its status changes to Closed, your name and the time are recorded, and from that moment every posting dated in that month is refused: journal entries, invoices, payments and inventory postings alike.

Lock Period is the stronger step for months that have been reported or audited. A locked month cannot simply be reopened.

Step 2 — What happens to a late posting

The late June bill is not lost. Post it with a date in the first open period (July) and note the original date in its description. June's numbers stay exactly as reported; the correction is visible where it was made.

If the amount really must be in June, the period has to be reopened. That is Step 3.

Step 3 — Reopening is an authorised act

Choose Reopen Period next to the month.

What you see: an *Admin action* warning that this *may affect finalized reports*, the period it applies to (June 2026), and a separate Reopen Period confirmation. Cancel leaves everything as it was.

After you confirm: the month is open again, postings can be dated in it, and any report generated for it should be re-run. When the correction is done, close it again; the new close is recorded with its own name and time.

What you have at the end

• Months that stay final once they are closed.
• Late documents posted where they belong, with the correction visible.
• A record of who closed, reopened and locked each month, and when.

Screenshots come from the Otiox demo workspace. Choose Switch to demo in the sidebar to follow along; changes there never touch live data.