Locked Periods lock existing, dated transactions, not allowing any changes or additions.
Locked Periods prevent the addition of new transactions any time in the locked period.
Clicking on the Lock icon on a dated transaction may say, Locked by Locked Period.
Your bookkeeper or system administrator chose to Lock past periods to protect data.
Locking options include for invoices only, excepting select users, back to a select date. Contact support@bigbusiness.com for help administering these features and options.