Cost of Goods
Use a similar prediction method to forecast what your goods will cost for future quarters or months. Account for expected fluctuations in sales, as that will affect your purchases for your goods. Once you have your totals for the expected cost of goods, subtract that total from the expected sales. Your sales total minus your cost of goods total is your gross margin. Now that you have this number you can use it against totals of all your other costs to predict your operating income.
Other Costs
Depending upon the size of your company, you will have any number of other operating costs to estimate. Some examples include payroll for employees, insurance for employees, overhead costs for maintaining a physical shop or warehouse, travel fees, and research and development costs. Record your previous expenses in the categories relevant to your business and use those numbers to predict the expenses over the course of the next year. Subtract that total from your gross margin to determine your operating income.
Taxes
Now that you have estimated your operating income, you can estimate your annual taxes. When you subtract your predicted taxes from your likely operating income you will discover your business's net income, the final step in the preparation of your operating budget. As you progress over the next fiscal year, compare your profits and expenses to those you predicted in your operating budget. If you did not use as much money as you expected in certain areas, move that money to other areas. If you are showing losses, you may need to consider layoffs or cutbacks on fringe benefits to compensate better next year.