In most states sole proprietors and partnerships aren't required to purchase workers compensation unless and until they have employees who aren't owners. Most states will allow sole proprietors and partners to cover themselves for workers comp if they choose to. Some states don't require employees to be covered if they are paid solely on commission.

Employees are generally defined as people performing services at the direction of the employer, for hire, including minors and workers who are not citizens.

Many states exempt employers with only a few employees from mandatory coverage laws. The threshold number of employees that triggers mandatory insurance is either three, four or five, depending on the state. Texas is the only state in which workers comp insurance is truly optional.

In some states, business owners' immediate family members' parents, spouse, and children who work for the firm may not have to be counted as employees for purposes of determining whether you must have workers comp insurance. These exceptions usually do not apply to other family members, such as sisters, brothers or in-laws.

Under some laws, independent contractors are not considered to be your employees. However, for the purpose of workers comp insurance, most states will treat an uninsured contractor or subcontractor or employees of an uninsured subcontractor as your employee, meaning you may be liable if he or she is injured while working for you. To avoid any unintended liability, larger companies often require any contractors or subcontractors doing work for them to provide proof they have workers comp insurance.

Regardless of whether insurance is required and regardless of how few employees you have, if an employee protected by the state statute is injured or killed in the course of working for you, you may be legally liable. One claim for a serious employee injury could bankrupt many small businesses. Insurance, through the payment of premiums for workers comp coverage, provides a predictable cost for handling this risk.