Glad you asked...
Take the total amount of your sales and deduct expenses. The number you get is the earnings before interest an taxes, or the EBIT number which is then taxed.
Then again, this answer might help you...
EBIT (Earnings before Income Taxes) is easy to calculate and is defined as the operating, profitable income or earnings before interest and taxes. The formula to calculate EBIT is as follows: EBIT = Revenue - Operating Expenses.

