How can I add invoices to past reconcile income ?

Hi sahar1,

When an account has been reconciled, you may need to undo the reconciliation for that period, so your financial report is accurate. 

You can either ask your accountant to undo the entire reconciliation or follow these steps to manually do it:

1. Go to Accounting tab and select Charts of Accounts.
2. Locate the account, and click View Register from the ACTION column.
3. Filter the Date and in the Reconcile status column (indicated by a check mark), click the field that shows R until it is blank. C - Cleared, R - Reconciled, and Blank - Not cleared or reconciled
4. Click Save.

Then, follow these steps to add an invoice:

1. Go to the + New > Invoice.
2. Click the customer's name from the drop-down menu.
3. Select the Invoice date, Due date, Product/Service, and Amount.
4. Click Save and close.

Once done, you can follow these steps on how to Record Invoice Payments.

Finally, reconcile the account again. 

I'm adding these articles for reference:

• Undo and remove transactions from reconciliations in QuickBooks Online
• Create invoices in QuickBooks Online
• Reconcile an account in QuickBooks Online

Please let me know if there's anything else you need. Thanks.