Patient Matching Improvement Act of 2021 This bill requires the Office of the National Coordinator for Health Information Technology (ONC) to standardize the format of postal addresses in health information technology to improve patient matching. Patient matching is the identification and linking of one patient's data within and across health care organizations using multiple demographic fields, such as name and address. The ONC must collaborate with the U.S. Postal Service (USPS) to make existing tools that automatically format addresses into a specific standard available to health care organizations. In particular, the ONC must focus on making the tools available to laboratories that test for COVID-19 (i.e., coronavirus disease 2019) to improve data collection related to that disease. If the USPS determines the tools cannot be made available to health care organizations, the Department of Health and Human Services must report to Congress on the barriers that prevent such use. In addition, the ONC must update regulations to require the use of a standard address format as a condition of certification for health information technology.