Hi there,
I can see how vital it is to be able to import IIF files into your account. I'll be happy to share some insights about importing files in QuickBooks (QBO).
At this time, QBO doesn't accept IIF files. If you wish to import your files, you'll have to use either a CSV (Comma Separated Value) or XLS/XLSX.
For additional reference and detailed instruction, please check the links below:
In case you have other questions, don't hesitate to reach out. I'll be on standby ready to help. :)