Some financial institutions (FI) provide transaction data in an Intuit Interchange Format (IIF) file. You must download IIF files to your hard drive from your FI Web site and then import them into QuickBooks.
When you import the IIF file, you may notice that transactions aren't flowing where they should, not showing up at all, or other strange behaviors
To Troubleshoot IIF Import Files for Online Banking:
Important: If you see the same results from your original file, then the IIF file is the issue, not the program or company file and you will need to contact the financial institution to resolve the issue as they might not be using a compatible version of IIF for QuickBooks. It is recommended to use .QBO files (QuickBooks Web Connect) to import transactions from your bank. Ask your bank if they support this format.
If the problem does not occur in the new file, then the IIF file is good and properly formatted for QuickBooks. You will need additional troubleshooting in your company data file. Possible fixes could be running a rebuild and merging bank accounts that are used in the IIF file, etc.