'federal subsidies for insurance available only through those exchanges set up by the states themselves. So, while the federal government has the power to create exchanges in the states that refuse to do so, it cannot offer subsidies through federally run exchanges.
Moreover, it is those subsidies that actually trigger the penalty under Obamacare for employers who fail to provide workers with insurance. Obamacare requires employers with 50 or more workers to provide health insurance or pay a tax, but only if at least one employee qualifies for subsidies under the exchange. Therefore, if subsidies can only be provided by state-authorized exchanges, a state potentially could block the employer mandate altogether , simply by refusing to establish the exchange.
The Obama administration and the IRS, unsurprisingly, have claimed they have the right unilaterally rewrite the law, yet again, to close this loophole. But, at the very least, this would be open to legal challenge. And perhaps the next time the Supreme Court will get it right.