There are two ways a transaction can be locked: if it’s included in a bank reconciliation or if it’s included in a compliance report. Both of these will require you to unlock the transaction to edit it.
Attempting to add a transaction that is before the end date of the most recent periodic compliance report will generate a warning. This is on a per-filer basis. Attempting to add a transaction that is before the end date of the most recent reconciliation will generate a warning. This is on a per-financial account basis.
