When you use the "New Refund Credit Balance" function in SwimOffice to make a refund, it goes into the IIF file as a payment type of "Other." This amount will obviously be negative unless you also enter payments of type “Other” that equal or exceed the refunds.
When payments of type “Other” are negative for a given month (due to more refunds than payments) and you try importing an IIF file into QuickBooks, it will give the error “Can’t record a negative payment.”
To fix this, you will need to delete the three lines of payment type “Other” in the IIF file (use some kind of text editor to do so), then try importing it again. They are near the top of the file, and the lines begin like so:
TRNS ... Other -1234.00
SPL ... 1234.00
You are welcome to contact TU Support for assistance with this (click the red question mark in the lower right corner of your TU website to do this).
You will also need to manually enter that refund amount into QB since it could not be imported.
Alternatives to view IIF files
How QuickBooks views refunds made in SwimOffice