Odoo Accounting software uses lock dates to prevent changes to closed accounting periods. You set a monthly lock date (like the 10th of the following month) and a fiscal lock date for year-end. Once locked, users cannot modify, create, or delete entries dated within those periods. Odoo Accounting features include the ability to set separate lock dates for posting entries versus creating invoices. For Odoo Accounting GST, this ensures your tax filings remain consistent after submission. You can also enable „secure entries“ which adds tamper-evident hashing to posted journal items for audit protection.