Assuming you are starting a business in the United States, the answer is generally yes, you can deduct business start up costs. The IRS allows you to deduct $5,000 in business start up costs in the year you start your business, and $5,000 in business start up costs in the first year your business is operational. Beyond that, you can deduct a wide variety of business expenses, including office expenses, marketing and advertising expenses, and travel expenses. You can deduct these expenses whether you are a sole proprietor, partnership, or corporation.