The OLD WAY to set a marketing budget was by picking a percent of sales.
Its more EFFECTIVE to base marketing expenditures on your practice's GOALS and OBJECTIVES.
You should seek a particular level of return and identify what you are willing to spend for this ROI.
Step 1: Determine your 12-month revenue collection trend as it is now. ( Overall or pertaining to a particular segment that the practice wants to grow.)
Step 2: Pick a timeframe and estimate where you'll end up if you do nothing.
Step 3: Establish a revenue goal that you can reasonably achieve. (Take into account the practice's competition, specialty area, referral base, size, etc.)
Step 4: Subtract your Step 2 estimate from your step 3 revenue goal.
Step 5: Use this "real" growth to determine an expected ROI goal for marketing -- what level of revenue you will need to bring in for every dollar you spend on marketing.
Results will vary based on practice history, local environment, reputation, capacity and other factors.