Bill Meltzer of HR Benefits Alert has a good article on budgeting for wellness programs. It provides a quick overview of the two main methods companies use to budget for corporate wellness programs.
The Top-Down Budget, where a fixed amount of money is devoted to the wellness program and you need to keep spending within the limits
The Zero-Based Budget, where you’re expected to deliver a program at no net costs to the company
Meltzer has some other great advice in other posts, including this one on Five Keys to Success for wellness programs.