According to the Census Bureau, of the 46 million Americans who are uninsured: 10.1 million are individuals who have income of $66,000 for a family of four, but who elect to remain uninsured. 9.3 million are non-citizens who generally do not pay tax. 6.4 million who are enrolled in Medicaid or S-CHIP but reported to the Census taker that they were not. (This phenomenon is known among statisticians as the Medicaid undercount.) 4.3 million are eligible for Medicaid or S-CHIP but have not enrolled. 5 million are childless adults, mainly healthy, young adults who simply do not wish to pay for insurance.