Disability insurance replaces a portion of your income if you’re unable to work due to an injury or illness. Typically, short-term disability covers illnesses, accidental injuries and maternity leave. Long-term disability sometimes will go into effect when short-term leaves off for health issues such as cancer, heart conditions or some types of mental health disorders. There is usually some sort of waiting period before disability payments begin, and they can either be a flat amount selected by the enrollee or a two-thirds percentage of pre-disability income range.