Smaller companies can often benefit from looking at the financial statements of their larger publicly-traded counterparts.  If you are an SaaS business much of your revenue likely comes from customers that pay with a credit card.  I looked through Rick Sherman’s On-Demand Index to find publicly-traded SaaS businesses and picked through the financial statements of those businesses, looking for those that 1. Get 100% of revenue from credit card payments and 2. Disclose those fees in their 10-K annual financial disclosure.

I am not done, but for the time being have found 1 company that meets that spec – Constant Contact.  Constant Contact provides software that helps businesses manage email lists.  From  Constant Contacts 2007 10-K (P.37):

Cost of revenue for 2007 was $13.0 million, an increase of $5.2 million, or 67%, over cost of revenue of $7.8 million for 2006…Of the increase in cost of revenue…$700,000 related to increased credit card fees due to a higher volume of billing transactions.

So, credit card processing fees increased by $700k.  We also can find on P. 31 of that same report that revenue in 2007 was $50.495M, an increase of $22.943M over the $27.552M the company earned in 2006. Let’s divide the increase in credit card processing costs into the increase in revenue (700,000 / 22,943,000) = 3.05%.  We can conclude from this analysis that Constant Contact is paying about 3.05% of revenue to its credit card processor.

We can also calculate that Constant Contact paid somewhere around $1.54M in credit card processing fees in 2007 ($50.495M x 3.05%).