Thanks for reaching out to us on the Community page,
You cant import iif data into quickbooks online you would need to convert it to a csv file first then import it into QuickBooks online.
Currently there is no option to import the data via a iif file like desktop it will have to get converted to a csv file, to be able to import it into the online product. I would suggest leaving feedback about this.
Welcome to the Community, @dmlbeach.
I'd be delighted to share some information on how you can import CSV files to QuickBooks.
If you're trying to import bank transactions, here are the factors to consider before you import the CSV file:
Also, you can use either of these formats:
Once the CSV file is prepared, you can start the importing process. Here's how:
Once completed, you can now start reviewing and categorizing each bank transaction. Also, you can refer to these articles for the step-by-step instructions about importing data in QuickBooks:
Lastly, you can read through these articles to help you resolve any errors you'd encounter during the importing process:
Stay in touch if you have additional questions about QBO. I'll be around to help you. Wishing you continued success.