In health policy, “crowd out” or “substitution” occurs when public funds substitute private dollars that otherwise would have been spent on health care. It is an inevitable consequence of any effort to subsidize coverage for people in America’s voluntary health care system where individuals and their employers can drop private coverage when better, more affordable public options are available. It is important to highlight that crowd out is not an issue linked only with expansions in publicly-subsidized health insurance programs. To the contrary, it occurs whenever the government takes steps to subsidize coverage, including through the tax code.