Intuit Interchange Format

The IIF file format, Intuit Interchange Format is a proprietary text file used by Intuit's Quickbooks software for importing and exporting lists and transactions.

As of 2004 QuickBooks can also import data using the XML-based qbXML file exchange format.

Intuit maintains information on .iif files including how to properly format and create them at http://support.quickbooks.intuit.com/support/Articles/HOW12778.