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For plan years beginning in calendar year 2027, the Applicable Percentage Table and the Section 36B Required Contribution Percentage indexing adjustments are based on the most recent projections of premium growth and income growth.2 See §§ 1.36B- 2(c)(3)(v)(C) and 1.36B-3(g). In addition, the additional adjustment provided in § 36B(b)(3)(A)(ii)(II) is not required for plan years beginning in 2027 because the Department of the Treasury (Treasury Department) and the Internal Revenue Service (IRS) have determined that the failsafe exception described in § 36B(b)(3)(A)(ii)(III) applies for plan years beginning in calendar year 2027. SECTION 2. CHANGE TO PREMIUM GROWTH ADJUSTMENT METHODOLOGY The Applicable Percentage Table and the Section 36B Required Contribution Percentage indexing adjustments are computed using the methodology described in section 4 of Rev. Proc. 2014-37, 2014-33 I.R.B. 363, and in guidance issued by the Department of Health and Human Services (HHS). For 2025 and a number of years prior to 2025, the rate of premium growth was based on per enrollee spending for employer-sponsored insurance as published in the National Health Expenditure Account. However, beginning in calendar year 2026, HHS guidance provided a new premium growth measure that captures increases in individual market premiums in addition to increases in employer-sponsored insurance premiums for purposes of calculating the premium adjustment percentage for the 2026 benefit year and beyond. See HHS Marketplace Integrity and Affordability rule, 90 Fed. Reg. 27074 (June 25, 2025). For taxable year 2027, the Treasury Department and the IRS will use the

2 The rate of premium growth and the rate of income growth are calculated using the NHEA Projections, 2025-2034, available at: https://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trends- and-Reports/NationalHealthExpendData/NationalHealthAccountsProjected.