Data collected under the auspices of the Home Mortgage Disclosure Act (HMDA) allow researchers and policymakers to identify and track important information about the mortgage market. Starting this year, additional data fields are due to be collected, revealing information that can help policymakers improve access to mortgages and avoid a repeat of the recent housing crisis. But proposed legislation gaining momentum in Congress as of April 2018 (the Home Mortgage Disclosure Adjustment Act in the House and the Economic Growth, Regulatory Relief, and Consumer Protection Act in the Senate) would curtail the collection of this new data. This brief demonstrates that while the proposed changes in the reporting rules appear to cut out information about a relatively small overall portion of the market, the impact on certain, particularly vulnerable market segments and geographic areas could be significant.