Business income is income received when products or services are sold. For example, fees are business income to a professional person.
Rents are business income to a person in the real estate business.
Income received in the form of property or services must be included in income at its fair market value on the date received. Normally a business is conducted as either a sole proprietorship, partnership, or corporation. A sole proprietorship is the simplest form of business organization. It has no existence apart from its owner. Business debts become personal debts of the owner.