Proposed Provision: A9. For single/head-of-household/married-filing-separate taxpayers with modified adjusted gross income (MAGI) below $85,000 and for joint filers with MAGI below $170,000 for the prior tax year, 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 2018 COLA. For those beneficiaries whose MAGI is above the $85,000/$170,000 for the prior tax year, provide no COLA. Index the eligibility income threshold amounts to the CPI-U after December 2018.