The Internal Revenue Service (IRS) posted a proposed rule to expand the range of tax data shared with the US Census Bureau for research and statistical purposes on March 29, 2024. In response, Urban Institute researchers provided a public comment on the implications of the proposed rule based on their expertise in taxes, health care, income and public benefits, race and equity, and statistical data privacy. Overall, the comment shared that expanding the range of tax data shared with the US Census Bureau, while ensuring the privacy and confidentiality of the blended data, will aid research and policy analyses on the impacts of the US federal tax system and other public programs. In doing so, the proposed rule has the potential to inform reforms that will improve the effectiveness and fairness of the federal tax system and other policies, and advance upward mobility and equity for families across the US.