; top bracket threshold For purposes of this section— (A) Zero bracket threshold The zero bracket threshold is $50,000,000. (B) Top bracket threshold The top bracket threshold is $1,000,000,000. (c) Applicable percentage (1) In general For purposes of this section, the applicable percentage is— (A) except as provided in subparagraph (B), 3 percent, and (B) in the case of any calendar year in which there is in effect legislation which meets the requirements of paragraph (2), 6 percent. (2) Legislation described Legislation meets the requirements of this paragraph if such legislation— (A) establishes a health insurance program that provides to all residents of the United States comprehensive protection against the costs of health care and health-related services, and (B) prohibits private entities from providing duplicate benefits. (d) Treatment of married individuals For purposes of this section, individuals who are married (as defined in section 7703) shall be treated as one taxpayer. (e) Treatment of nongrantor multibeneficiary trusts (1) In general Any trust or portion of a trust which is a nongrantor multibeneficiary trust shall be treated as an individual to whom this chapter applies. (2) Computation of tax (A) In general In applying this chapter to a nongrantor multibeneficiary trust— (i) the zero bracket threshold shall be equal to the sum of— (I) $0, plus (II) the lowest unused 0 percent bracket amount assigned to the trust by all beneficiaries of the trust, and (ii) the top bracket threshold shall be equal to the sum of— (I) $0, plus (II) the lowest unused 2 percent bracket amount assigned to the trust by all beneficiaries of the trust. (B) Unused 0 percent bracket amount For purposes of this paragraph, the term unused 0 percent bracket amount means, with respect to any beneficiary for any calendar year, the lesser of— (i) the excess (if any) of— (I) the zero bracket threshold, over (II) the sum of— (aa) the net value of all taxable assets of the beneficiary for the calendar year, plus (bb) any unused 0