Maintaining up-to-date provider directories is necessary as CMS can fine insurers with outdated directories. As a condition of participation, UnitedHealthcare requires that providers notify them of changes, but also has a Professional Verification Outreach program to proactively request information from providers. However, providers are burdened by having to maintain their information with multiple networks (e.g., competitors to UnitedHealthcare). The total cost of maintaining these directories is estimated at $2.1b annually, and a blockchain initiative began in 2018 to share the directory.