The Affordable Care Act has once again made its way onto the Supreme Court’s calendar.  On Friday, the Justices voted to accept King v. Burwell for hearing this term.  The issue this time is whether tax subsidies may be given to individuals who purchase insurance through the federal exchange, rather than an insurance exchange run by one of the states.   The Urban Institute has estimated that 7.3 million people are expected to receive subsidies as a result of enrolling through a federally-facilitated exchange.  This question has spill-over effects for the employer mandate, which triggers penalties for an employer when an employee purchases insurance through an exchange and receives a subsidy.  Argument has not yet been scheduled but will likely occur after the first week of March, with a decision likely to come at the end of the term in June or July, as observed by SCOTUSblog.
Since only 14 states are operating their own exchanges, the federal government is involved in some manner in the exchanges in the other 36 states.  So far, individuals meeting certain income levels who buy their insurance on either a state exchange or a federally-administered exchange have been receiving tax subsidies, pursuant to the IRS’ interpretation set out at 26 C.F.R. §1.36B-2(a)(1).  The plaintiffs in King v. Burwell, though, argue that the statute only provides subsidies for people who purchase insurance from “an Exchange established by the State,” (26 U.S.C. §36B(c)(2)(A)(i)) so subsidies aren’t allowed for individuals who purchase on a federally-administered exchange. 
The Courts of Appeals for the Fourth Circuit and the D.C. Circuit have weighed in so far.  On July 22, a panel of the Fourth Circuit held that subsidies were available for participants in federal exchanges.  On the same day, a panel of the D.C. Circuit held in Halbig v. Burwell that the opposite – that subsidies are only allowed for people buying insurance on state-run exchanges.  On September 4, though, the judges of the D.C. Circuit vacated the decision in Halbig v. Burwell  and voted to hear the case en banc, meaning all the judges, not just the three that originally heard the case, would hear arguments and vote on the decision.
It is an unusual move that the Court would accept the issue onto its docket while the D.C. Circuit’s en banc proceedings are still pending and no circuit split exists, as noted by commentators here and here.  It may mean that the Court is interested in providing a swift decision to settle the issue that effects so many Americans. 
The Court has already issued two ACA decisions, National Federation of Independent Business v. Sebelius (holding the individual mandate to be constitutional and the Medicaid expansion voluntary) and Burwell v. Hobby Lobby Stores, Inc. (holding that the law could not require private companies to provide contraception over religious objections).