Section 425.656 - Calculating the regional adjustment to the historical benchmark(a)General. This section describes the methodology for calculating the regional adjustment to the historical benchmark based on the ACO's regional service area expenditures, making separate calculations for the following populations of beneficiaries: ESRD, disabled, aged/dual eligible Medicare and Medicaid beneficiaries, and aged/non-dual eligible Medicare and Medicaid beneficiaries. This section applies to regional adjustment calculations for agreement periods beginning on January 1, 2024, and in subsequent years.(b)Calculation of an average per capita expenditure amount for the ACO's regional service area. To compute an average per capita expenditure amount for the ACO's regional service area, CMS does all of the following:(1) Determines the counties included in the ACO's regional service area based on the ACO's BY3 assigned beneficiary population.(2) Determines the ACO's regional expenditures as specified under § 425.654 for BY3.(3) Adjusts for differences in severity and case mix between the ACO's assigned beneficiary population for BY3 and the assignable population of beneficiaries for the ACO's regional service area for BY3. The assignable population of beneficiaries is identified for BY3 using the assignment window or expanded window for assignment that is consistent with the beneficiary assignment methodology selected by the ACO for the performance year according to § 425.400(a)(4)(ii) .(c)Calculation of the adjustment. To calculate the adjustment, CMS does all of the following:(1) Determines the difference between the average per capita amount of expenditures for the ACO's regional service area as specified under paragraph (b)(1) of this section and the average per capita amount of the ACO's historical benchmark determined under § 425.652(a)(1) through (7) and (c)(2) , for each of the following populations of beneficiaries:(iii) Aged/dual eligible Medicare and Medicaid beneficiaries.(iv) Aged/non-dual eligible Medicare and Medicaid beneficiaries.(2) Applies a percentage, as determined in paragraph (e) of this section.(3) Caps the per capita dollar amount for each Medicare enrollment type (ESRD, disabled, aged/dual eligible Medicare and Medicaid beneficiaries, aged/non-dual eligible Medicare and Medicaid beneficiaries) calculated under paragraph (c)(2) of this section at a dollar amount equal to a percentage of national per capita expenditures for Parts A and B services under the original Medicare fee-for-service program in BY3 for assignable beneficiaries in that enrollment type identified for the 12-month calendar year corresponding to BY3 using data from the CMS Office of the Actuary. The cap is applied as follows: (i) For positive adjustments, the per capita dollar amount for a Medicare enrollment type is capped at 5 percent of the national per capita expenditure amount for the enrollment type for BY3.(ii) For negative adjustments, the per capita dollar amount for a Medicare enrollment type is capped at negative 1.5 percent of the national per capita expenditure amount for the enrollment type for BY3.(4) For negative adjustments, CMS will multiply the regional adjustments calculated in paragraphs (c)(2) or (3) of this section by 1 minus an offset factor equal to the sum of the following- (i) Proportion of the ACO's BY3 assigned beneficiaries that are dually eligible for Medicare and Medicaid; and(ii) The difference between the ACO's weighted average prospective HCC risk score for BY3 taken across the four Medicare enrollment types and 1. When calculating the weighted average prospective HCC risk score, the weight applied to the prospective HCC risk score for BY3 for each Medicare enrollment type is equal to the product of the BY3 per capita expenditures for that enrollment type and the BY3 person years for that enrollment type.(5) The offset factor described in paragraph (c)(4) of this section is subject to a minimum value of zero (representing no offset to the negative regional adjustment) and a maximum value of 1 (representing a full offset to the negative regional adjustment).(d)Expression of the regional adjustment as a single value.(1) CMS expresses the regional adjustment as a single value by taking a person-year weighted average of the Medicare enrollment type-specific regional adjustment values determined in paragraph (c) of this section.(2) CMS uses the regional adjustment expressed as a single value for purposes of determining the adjustment, if any, that will be applied to the benchmark in accordance with § 425.652(a)(8) .(e)Phase-in of weights used in regional adjustment calculation.(1) The first time that an ACO's benchmark is adjusted based on the ACO's regional service area expenditures, CMS calculates the regional adjustment as follows: (i) Using 35 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's initial or rebased historical benchmark, if the ACO is determined to have lower spending than the ACO's regional service area.(ii) Using 15 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's initial or rebased historical benchmark, if the ACO is determined to have higher spending than the ACO's regional service area.(2) The second time that an ACO's benchmark is adjusted based on the ACO's regional service area expenditures, CMS calculates the regional adjustment as follows: (i) Using 50 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's rebased historical benchmark if the ACO is determined to have lower spending than the ACO's regional service area.(ii) Using 25 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's rebased historical benchmark if the ACO is determined to have higher spending than the ACO's regional service area.(3) The third time that an ACO's benchmark is adjusted based on the ACO's regional service area expenditures, CMS calculates the regional adjustment as follows:(i) Using 50 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's rebased historical benchmark if the ACO is determined to have lower spending than the ACO's regional service area.(ii) Using 35 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's rebased historical benchmark if the ACO is determined to have higher spending than the ACO's regional service area.(4) The fourth or subsequent time that an ACO's benchmark is adjusted based on the ACO's regional service area expenditures, CMS calculates the regional adjustment to the historical benchmark using 50 percent of the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's rebased historical benchmark.(5) To determine if an ACO has lower or higher spending compared to the ACO's regional service area, CMS does the following:(i) Multiplies the difference between the average per capita amount of expenditures for the ACO's regional service area and the average per capita amount of the ACO's historical benchmark for each population of beneficiaries (ESRD, disabled, aged/dual eligible Medicare and Medicaid beneficiaries, aged/non-dual eligible Medicare and Medicaid beneficiaries) as calculated under paragraph (c)(1) of this section by the applicable proportion of the ACO's assigned beneficiary population (ESRD, disabled, aged/dual eligible Medicare and Medicaid beneficiaries, aged/non-dual eligible Medicare and Medicaid beneficiaries) for BY3 of the historical benchmark.(ii) Sums the amounts determined in paragraph (e)(5)(i) of this section across the populations of beneficiaries (ESRD, disabled, aged/dual eligible Medicare and Medicaid beneficiaries, aged/non-dual eligible Medicare and Medicaid beneficiaries).(iii) If the resulting sum is a net positive value, the ACO is considered to have lower spending compared to the ACO's regional service area. If the resulting sum is a net negative value, the ACO is considered to have higher spending compared to the ACO's regional service area.(iv) If during the term of the agreement period CMS adjusts the ACO's benchmark, as specified in § 425.652(a)(9) , CMS redetermines whether the ACO is considered to have lower spending or higher spending compared to the ACO's regional service area for purposes of determining the percentage in paragraphs (e)(1) through (3) of this section used in calculating the regional adjustment.(f)Special rules for determining the weights used in the regional adjustment calculation for a re-entering ACO. For a re-entering ACO whose prior agreement period benchmark was calculated according to § 425.603(c) , CMS determines the weight used in the regional adjustment calculation described in paragraphs (b) through (e) of this section by considering the agreement period the ACO is entering into according to § 425.600(f) in combination with either of the following- (1) The weight previously applied to calculate the regional adjustment to the ACO's benchmark under § 425.603(c)(9) in its most recent prior agreement period; or(2) For a new ACO identified as a re-entering ACO, CMS considers the weight previously applied to calculate the regional adjustment to the benchmark under § 425.603(c)(9) in its most recent prior agreement period of the ACO in which the majority of the new ACO's participants were participating previously.87 FR 70246, Nov. 18, 2022, as amended at 88 FR 79550, Nov. 16, 2023 87 FR 70246, 1/1/2023; 88 FR 79550, 1/1/2024