TPC's 2021 Tax Model Technical Updates

The Urban-Brookings Tax Policy Center (TPC) large-scale microsimulation model produces estimates of how current and proposed tax policies will affect federal revenues and the distribution of tax burdens by income. The model is similar to those used by the Congressional Budget Office (CBO), the Joint Committee on Taxation (JCT), and the Treasury's Office of Tax Analysis (OTA). This year, TPC updated and revised its tax model in a variety of ways. In addition to incorporating new economic and budgetary projections published by the Congressional Budget Office (CBO) in January 2021, we implemented a new version of an algorithm to enable a streamlined update based on substantially revised CBO projections published in July 2021. We also incorporated major legislation enacted in response to the COVID-19 pandemic, including the American Rescue Plan (ARP) Act of 2021 and the Coronavirus Aid, Relief, and Economic Security (CARES) Act of 2020. Those updates enabled our distributional analyses of tax proposals in President Biden’s fiscal year 2022 budget and various versions of the Build Back Better package, as well as a number of narrower proposals.