Why when I reconcile the balance is double rather become zero?

Hello there, @ABEE.

I'm glad to assist you today so we can figure out what's causing your balance to be doubled when reconciling.

When you reconcile an account, you need to compare each transaction on your bank statement with statements entered into QuickBooks. If everything matches, you know accounts are balanced and accurate. If not, here are a few reasons why QuickBooks Online reconciliation discrepancies occur:

• Someone entered an incorrect ending balance at the start of the reconciliation.
• There are missing or duplicate transactions in QuickBooks.
• Someone entered transactions into QuickBooks that haven't cleared your bank yet.

To fix this, I recommend reviewing your opening, beginning, and ending balances first to be sure you've ruled out any possible errors. After which, you can now go ahead and unreconcile the transaction. Note that primary admins can only undo a reconciliation one transaction at a time given that they know what needs to be changed. 

However, if you need to completely start over, you'll need to reach out to your accountant or use a QuickBooks Online Accountant (QBOA) account to undo the entire reconciliation in order to correct this ending balance. Only an accountant has the option to undo entire reconciliations. You will then need to reconcile your statements once again.

Check out this article for more information about the process: Undo or remove transactions from reconciliations in QuickBooks Online. 

Additionally, I've attached an article to help you make sure that all of your transactions are placed in the appropriate account to prevent issues: Learn about the chart of accounts in QuickBooks Online. 

Stay connected with me if you have more questions about reconciliation in QuickBooks Online. I'll be around to help. Have a great day!