This is a good article on Budgeting for Fluctuating Revenue by E-Myth.
As many business owners are painfully aware, it’s not an easy thing to create an operating budget for a business whose revenues tend to be all over the map. Yet this is the reality for many businesses. The need to create and use a realistic budget is increasingly pressing in today’s economy, but how do you do that effectively and accurately? Especially if your business revenue fluctuates significantly month to month?
Read the full article at http://www.e-myth.com/cs/user/print/post/budgeting-for-fluctuating-revenue.