https://www.odoo.com/forum/help-1/question/how-to-create-the-opening-balance-in-accounts-10917

1) Create an Opening Entries Journal: In most of the Chart of Accounts this comes by default. If it's not present, create a journal "Opening Entries Journal" with Type="Opening/Closing Situation". Check the "Centralized Counterpart" option. 1a) create an Account "Opening Expense Account" of Internal Type="Regular" and Account Type="Expense" and set this as the Default Debit Account for the above journal 1b) create an Account "Opening Income Account" of Internal Type="Regular" and Account Type="Income" and set this as the Default Credit Account for the above journal