Health Insurance Portability and Accountability Act of 1996 HIPAA
The Act was enacted to make health insurance more "portable" from one employer to another. The law mandates procedures for both new hires and for existing employees who are leaving the company. Employees who are new to a company can use evidence of previous health care coverage that is provided by their former employer to reduce or eliminate the new employer's preexisting condition requirements. Employees who are leaving a company must be provided a certificate of prior creditable health care coverage to use for this purpose. The law includes other provisions regarding restrictions on preexisting conditions, special enrollment rights and privacy rights and protections.
Source: Society for Human Resource Management