Go to the Contacts module to select a contact and click ‘Link in QuickBooks’. Enter the QuickBooks customer ID number and click ‘OK’ to confirm. The customer ID number is the value after ‘nameId=’ in the URL address bar when you open the customer in QuickBooks Online.
Locating the QuickBooks Customer ID
The customer ID number can be found in the URL address when you open a selected customer in QuickBooks Online. In the example, the customer ID number for Tom Davis is ’12’.