When you convert an existing bank account into QuickBooks, you must perform the following steps to be able to reconcile the bank account for the first time:

1. Get your last reconciled bank statement. Enter the ending balance from the bank statement into the check register in QuickBooks as a deposit if positive or as a check if negative.
2. Enter each one of the transactions that were written in previous months that still have not cleared (shown up) on any of those bank statements.
3. Note: The difference between #1 and #2 above should be your actual bank register balance.
4. Perform the Reconcile function on that prior month through the Banking->Reconcile function.
5. QuickBooks will show the begining statement balance as $0.00, that’s ok; Just enter the actual ending statement balance in the appropriate field.
6. Check off the the transaction from #1 & #2 above.
7. The “Difference” amount should be $0.00 which means you are reconciled. Click “Reconcile Now” button.
8. You are now ready to reconcile the first bank statement (the following month’s bank statement).