Hi there, @mumana. Let me clarify a few things about importing customers into QuickBooks Online (QBO).
At this time, adding the corporate ID number in the csv file when importing the customer is unavailable.
Since there's no field to add the corporate ID number in the csv. What we can do is to manually enter the corporate ID number once you already have the customer's profile.
You can refer to these articles for detailed steps on importing customers' data and answers to frequently asked questions, such as the file format used in importing:
As always, should you need further assistance with your QBO, don't hesitate to leave a comment below. We're always here to help.
