Underestimating operating costs About a third of new business owners underestimate their monthly expenses. While founders remember the obvious expenses, they often forget related items that can quickly add up. For example, if you make a product, you also have to package it. If you need a car or truck for business, you also need auto insurance. These expenses can increase employee costs by up to 25 percent. To get an idea of what your costs will be, ask vendors what they'll charge you initially and what discounts they can offer as you buy in larger amounts. Talk to people in your line of business who aren't direct competitors about what they're expenses are and what they spent starting out.