Here’s an example calculation for an early payment on Kanexa.
If your invoice was worth $1,000.00 (USD), your payment terms were 60 days and you sold that invoice to a funder on day 40, you’d get 20 days’ worth of early payment.
If the interest rate is 6% per annum, the discount from your invoice would be $3.33, so your early payment would be $996.67.
=invoice value *(days early paid/days in year)* rate
20/360 x 1000 x 0.06%