IIF vs CSV: which QuickBooks import format should you use?

If you’re importing into QuickBooks, you’ll run into two formats: IIF and CSV. They aren’t interchangeable, and picking the wrong one wastes an afternoon. Here’s what each is and when to use it.

IIF (Intuit Interchange Format)

IIF is QuickBooks Desktop’s long-standing tab-delimited format. It can carry both lists (chart of accounts, customers, vendors, items) and certain transaction types. It’s powerful for Desktop but unforgiving: the structure is strict, error messages are terse, and a small formatting slip can reject a whole file.

• Use it for: bulk-loading lists and supported transactions into QuickBooks Desktop.
• Watch for: exact column headers, account references that must already exist, and limited validation before it writes.

CSV

CSV is the plain comma-separated format QuickBooks Online uses for its built-in imports (customers, vendors, chart of accounts, and via tools, transactions). It’s friendlier and more widely supported, but Online’s native CSV import covers fewer record types than IIF does on Desktop.

• Use it for: importing lists into QuickBooks Online, and transactions through supported tools.
• Watch for: field mapping during upload, and the narrower set of things Online will import natively.

Which should you use?

It’s mostly decided for you by the destination: Desktop leans IIF for lists and supported transactions, Online uses CSV. The harder part isn’t the format — it’s preparing clean, correctly typed data that either format will accept. A conversion tool that outputs the right format for your target, already validated, removes the choice entirely.