Calculation for Business Interest On Credit Card

[lilcupcakes09]

How do I figure out the business portion of interest on a personal credit card where both business & personal purchases were made throughout the year?

[LysesKids]

How do I figure out the business portion of interest on a personal credit card where both business & personal purchases were made throughout the year?

I need the same info... thankfully one card is business only, so that one is a no brainer, but my other 2?

[TomCopeland]

credit card interest

How do I figure out the business portion of interest on a personal credit card where both business & personal purchases were made throughout the year?

I wrote an article about calculating sales tax here: http://tomcopelandblog.com/qa-can-i-deduct-sales-tax
The principle is the same when calculating credit card interest.