Lock a bookkeeping period and handle later corrections

You send the August figures to your accountant. A week later, the same report has a different profit because someone added a bill dated in August. The bill may belong there, but everyone needs to know what changed and why.

Closing a period creates a review point. Locking it helps preserve that point. Neither replaces the underlying checks in the MYOB month-end routine.

Save the baseline before applying a lock

Complete the bank, card and other balance reconciliations. Review unpaid invoices, supplier bills, owner-related entries and unresolved transactions. Agree which exceptions are still open and whether they prevent the period being signed off.

Export the profit and loss report, balance sheet, trial balance, reconciliation reports and relevant tax reports. Record the reporting basis, dates, filters and export time. Keep the final exception list, approval and any lodged business activity statement (BAS) confirmation beside them.

Give the folder a useful name, such as “August close, approved 5 September”. Don't overwrite it when later corrections arrive. A downloaded report without its settings can be difficult to reproduce.

Set the date and permissions deliberately

Use the lock-date controls for your software and confirm who can change them. Xero's lock-date guidance describes restrictions on adding or editing transactions dated on or before the lock, with different controls for advisor access. A lock isn't an immutable archive; users with the appropriate authority can change it.

Ask the responsible administrator to confirm the effective date and access. Check the configuration or use a demonstration file to understand its behaviour. Don't add a fake transaction to the live accounts merely to test a lock.

Route a late bill through a correction decision

In this fictional example, August was reviewed on 5 September and locked through 31 August. On 8 September, a $330 supplier bill dated 27 August arrives. It relates to work carried out in August and hasn't been entered or paid.

5 September: baseline

August reports and reconciliations saved. Approval recorded. Transactions locked through 31 August.

8 September: late document

Bill L-27, $330, invoice date 27 August. Record when received, confirm it isn't duplicated and identify the period affected.

Before any change

Authorised reviewer decides accounting treatment. Registered agent checks GST basis, claim history and any lodged BAS impact.

After approval

Record the approved correction. Rerun affected reports, explain differences, restore the lock and save the revised version alongside the original.

Original ASBG period-close timeline. The bill amount is a fictional fact; the diagram does not prescribe its GST period or authorise reopening the file.

The bill's invoice date, the date the work occurred, payment date and date received can all matter for different purposes. Don't change a supplier document's date simply to bypass a lock. Ask the accountant how it should be recognised and retain the original document.

Separate a late GST claim from an error

The ATO's explanation of GST errors distinguishes an unclaimed goods and services tax (GST) credit later claimed from a GST error or adjustment. A late bill therefore doesn't automatically mean you must revise the earlier BAS.

Ask the registered agent whether the purchase is eligible, which reporting basis applies, whether GST was already claimed, and what documents and time limits matter. A duplicate claim is a different problem from a missed claim. The BAS lodgement guide covers the surrounding submission process, but your correction needs its own decision.

Record exactly what changed

Use a correction log with these fields:

If the period is reopened, limit the work to the approved change. Recheck the accounts affected and compare the new reports with the saved baseline. Explain any difference that exceeds the approved correction, then restore the lock and notify the people who received the old figures.

For a change to account structure, also use the chart-of-accounts mapping. Renaming and recoding can affect how earlier reports are read even when no new bill is added.

Key takeaways

• Save evidence and report settings before closing the period.
• Make late corrections through a named approval and review process.
• Retain both versions and explain the changes to report users.

Where to get help

Use your software's current lock-date documentation. Ask the accountant about recognition and the registered BAS or tax agent about any lodged statement impact. The bookkeeping and BAS collection links the checks that come before a period is locked.