Proposed Provision: A9. For single/head-of-household/married-filing-separate taxpayers with modified adjusted gross income (MAGI) below $117,300 and for joint filers with MAGI below $234,600 for December 2028 ($85,000 and $170,000 multiplied by estimated CPI-U for 2018-2028), use the chain-weighted version of the Consumer Price Index for All Urban Consumers (C-CPI-U) to calculate the cost-of-living adjustment (COLA), beginning with the December 2028 COLA. For those beneficiaries whose MAGI is above these thresholds, provide no COLA. Use prior tax year income data for this determination. Use the chain-weighted CPI for the COLA for years prior to benefit receipt. Index the eligibility income threshold amounts to the CPI-U after December 2028.