(case involves I.R.C. Sec. 36B credit which is designed to offset some of increase in health insurance premium costs caused by Obamacare; I.R.C. Sec. 36B(b)(2)(A) defines the "premium assistance amount" by referring to "the monthly premiums for...qualified health plans offered in the individual market...which were enrolled in through an Exchange established by the state under 1311 of the Patient Protection and Affordable Care Act..."; implementing regulation states that credit is available to enrollees in federally-facilitated Exchanges rather than just state Exchanges; plaintiffs were not eligible for government or employer-sponsored health insurance coverage and without the credit health insurance would not have been affordable to them and, hence, no penalty would apply for failing to obey the government dictate to buy health insurance; plaintiffs lived in state that had a federally-facilitated Exchange, thus the regulation now results in plaintiffs being penalized for failing to obey the government command to buy health insurance; court determined that plaintiffs case did not involve tax refund action (i.e., plaintiffs needed to buy insurance and waive their claims or don't buy insurance, get penalized and then file refund suit and recover only upon prevailing); court upheld regulation under Chevron (467 U.S. 837 (U.S. 1984)) deference standard).