gross income For purposes of this subsection, the term modified gross income means the adjusted gross income (as defined in section 62 of the Internal Revenue Code of 1986) of the taxpayer for the taxable year increased by any amount excluded from gross income under section 911, 931, or 933 of such Code. (5) Credits not allowed against tax, etc For purposes determining regular tax liability under section 26(b) of such Code, the increase in tax under this subsection shall not be treated as a tax imposed under chapter 1 of such Code. (6) Regulations The Secretary of the Treasury shall issue such regulations or other guidance as are necessary or appropriate to carry out this subsection, including requirements that the entity to whom premiums are reimbursed under section 6432(a) of the Internal Revenue Code of 1986 report to the Secretary, and to each assistance eligible individual, the amount of premium assistance provided under subsection (a) with respect to each such individual. (7) Effective date The provisions of this subsection shall apply to taxable years ending after the date of the enactment of this Act. 70308. Risk corridor program (a) In general The Secretary of Health and Human Services (in this section referred to as the Secretary ) shall establish and administer a program of risk corridors for plan years 2020 and 2021 under which the Secretary shall make payments to health insurance issuers offering health insurance coverage in the individual or small group market based on the ratio of the allowable costs of the coverage to the aggregate premiums of the coverage. (b) Payment methodology The Secretary shall provide under the program established under subsection (a) that if the allowable costs for a health insurance issuer offering health insurance coverage in the individual or small group market for any plan year are more than 105 percent of the target amount, the Secretary shall pay to the issuer an amount equal to 75 percent of the allowable costs in excess of 105 percent of the target amount. (c)