Locking a financial year means that no transactions during the specified date range can be created or modified. It is best to do this at the end of a tax year.
This will be based on the invoice/bill date or the accrual date (if you have the accrual feature enabled) i.e. if you create an invoice with an invoice date (or accrual date if enabled) within a locked period, the system will prevent you from confirming the invoice.
To correct overlapping periods or to sort them in chronological order, you can delete reporting periods and re-add them without affecting transactions.
Reporting periods are listed on the Settings > Accounting > Periods > Reporting Periods menu.
Click on the padlock icon to the right of the period you wish to lock. Any reporting period that you lock will display the locked padlock icon.
If you want to make changes to a transaction in a previous period, you must unlock all reporting period from the present back to the year in which the transaction falls.
You can also define your own custom locked period date ranges, for example for VAT quarters, by clicking on the Locking Periods tab.
Enter your own custom date range and hit Add.
You also have the option to lock all future dates, preventing transactions from being created in future, by ticking the checkbox and clicking Save.