Assume your new business is a retail establishment that is selling furniture and, as a promotion, you plan to give buyers 90 days to pay. Your working capital needs could be huge. First, you have to buy your inventory, then, after it sells, pay for the replacement inventory. This could mean that you will not receive one dollar to pay bills for at least 90 days after you open the doors. If you don't plan for this working capital need in advance, you probably won't even stay in business for 90 days.