Unlike your personal expenses, every business expense is tax-deductible to business expense is tax-deductible to some degree. The list of what counts as business expense is vast, and probably includes some things you wouldn't expect. When you have a good working knowledge of business expenses, it will help you develop a better picture of your company's profitability and help you manage your tax bill. It can also save you some money: When you know save you some money: When you know what your accountant will be looking for when he does your taxes, you can come in completely prepared.