The Supreme Court’s decision means that the Medicaid expansion is now an option for states, not a requirement. If states do not participate, experts have speculated that it could create a subset of people who earn too much to qualify for Medicaid — the exact threshold varies — but not enough to qualify for the tax credits that would help them pay for insurance. States will not have to pick up the added costs of the Medicaid expansion until 2016. After that, the federal government will gradually reduce its contribution until it reaches 90 percent of the costs by 2020.