If you have several months or even years of transactions in QuickBooks that have not been reconciled with your financial statements, you can reconcile them without having to do so one month at a time.
If your unreconciled transactions and statements span multiple fiscal years, the recommended method to reconcile them is one year at a time. Using that method, all adjustments, service fees, and interest you enter during the reconciliation process will apply to the year in which those transactions occurred. However, you may wish to consult with your accountant or attorney regarding the best method for you to reconcile statements and transactions for multiple years.
Reconcile 1 year at a time