I have been selling and valuing legal practices for 15 years. During that time I have analysed the financial statements of literally hundreds of firms.
When someone asks me questions such as how much rent should I be paying? How much should I pay my staff? What is a reasonable level of earnings? I can usually respond without too much difficulty.
For example, how much can I afford in occupancy costs? I will answer that the most common range is 5% to 10% of revenue per ann