An employer can require a doctor's note if one of its employees is taking a sick day, but the policy must be enforced uniformly. Additionally, the note must not be required to contain any private information about the employee's diagnosis.
Employers may also require a doctor's note if a patient is taking leave under the Family and Medical Leave Act (FMLA). However, employers cannot require notes for each individual absence unless it is time to re-certify the leave.
If a company is providing accommodations for someone who is temporarily or permanently disabled, the company may request a doctor's note related to the accommodation and its need.