What is IIF?

IIF is QuickBooks Desktop's import and export format: tab-separated, with several tables interleaved in one file. A line starting with an exclamation mark defines the columns for a record type, and the data lines that follow begin with that type's keyword.

Who uses it

QuickBooks Desktop users, and the bookkeepers who have to move data into and out of it.

Reading IIF

The largest table in the file is used, which is almost always the transactions. A typical export holds TRNS rows for the transactions and SPL rows for their split lines; those are two tables, not one, and combining them would produce a column layout that fits neither.

What it can hold

IIF is an accounting interchange format. QuickBooks' tab-separated import format, with a header line that names the record type. A machine can read the table back out of it without guessing, which is what makes it safe to convert into and out of.

It keeps

Its own record boundaries. A reader can take one row at a time without loading the file, and a copy that was cut off part way through still yields everything before the cut.
A header that is marked as one, rather than being the first row by convention.

It cannot express

A null. An absent value and an empty one look the same, and nothing in the file says which was meant.
Nesting. Cells are flat, so structured values have to be flattened into extra columns or written into one cell as text.
A line break inside a cell. One would end the row, so it has to be replaced before writing.
Any formatting. Bold, colour, column widths and merged cells have nowhere to go.

What it looks like

Example IIF

!TRNS	TRNSTYPE	DATE	ACCNT	NAME	AMOUNT	MEMO
!SPL	TRNSTYPE	DATE	ACCNT	NAME	AMOUNT	MEMO
!ENDTRNS
TRNS	CHECK	01/15/2026	Checking	Greenfield Grocers	-42.50	Weekly shop
SPL	CHECK	01/15/2026	Groceries	Greenfield Grocers	42.50	Weekly shop
ENDTRNS
TRNS	DEPOSIT	01/16/2026	Checking	Acme Ltd	1850.00	January salary
SPL	DEPOSIT	01/16/2026	Salary	Acme Ltd	-1850.00	January salary
ENDTRNS

Questions

Why does my IIF file have two sets of headers?

Because it holds two tables. TRNS lines are transactions and SPL lines are the splits belonging to them, and each has its own column definition. They are separate exports that happen to share a file.

How do I open IIF files?

Any text editor will show you the contents. To read it as a table, paste it into the converter on this site and it appears in an editable grid. Nothing is uploaded.

Is IIF a good format for sharing data?

It depends who is receiving it. QuickBooks Desktop users, and the bookkeepers who have to move data into and out of it. If the recipient is outside that group, a plain CSV travels further than anything else.