I'm here to guide you on how to import your client's information into QuickBooks Online.
First, you'll want to create a file of your client's contact information. You can import this information from Outlook, Excel, or Gmail. This Community article provides detailed steps on how to create the file. Once it's created, then you can import the file into QuickBooks Online. I've provided the steps below on how you can bring in this data:
Go to the Gear icon at the top-right of your QuickBooks Online account, then select Import Data.
Press on the Browse button to choose the file.
Hit Next and follow the on-screen instructions to import the data.
At this time, there's not a way to import the client's payment history into QuickBooks Online. I'm going to submit feedback to our Product Development Team about bringing in a feature that will allow this to happen. In the meantime, you can visit our Blog to see updates to our products, as well as see what's coming in the future.
If you have any additional questions or concerns, please don't hesitate and reach back out! Have a beautiful day.