If a qualified health plan under section 18022(b)(5) of this title offers benefits in addition to the essential health benefits required to be provided by the plan, or a State requires a qualified health plan under section 18031(d)(3)(B) of this title to cover benefits in addition to the essential health benefits required to be provided by the plan, the reductions in cost-sharing under this section shall not apply to such additional benefits.
If an individual enrolls in both a qualified health plan and a plan described in section 18031(d)(2)(B)(ii)(I)  of this title for any plan year, subsection (a) shall not apply to that portion of any reduction in cost-sharing under subsection (c) that (under regulations prescribed by the Secretary) is properly allocable to pediatric dental benefits which are included in the essential health benefits required to be provided by a qualified health plan under section 18022(b)(1)(J) of this title.
For purposes of this section, an individual shall be treated as lawfully present only if the individual is, and is reasonably expected to be for the entire period of enrollment for which the cost-sharing reduction under this section is being claimed, a citizen or national of the United States or an alien lawfully present in the United States.
The Secretary, in consultation with the Secretary of the Treasury, shall prescribe rules setting forth the methods by which calculations of family size and household income are made for purposes of this subsection. Such rules shall be designed to ensure that the least burden is placed on individuals enrolling in qualified health plans through an Exchange and taxpayers eligible for the credit allowable under this section.
Any term used in this section which is also used in section 36B of title 26 shall have the meaning given such term by such section.