Leveraging Integrated Networks in Communities to Address Social Needs Act of 2021 or the LINC to Address Social Needs Act of 2021 This bill requires the Department of Health and Human Services (HHS) to award grants to better integrate health care and social services using technology platforms and related infrastructure. To receive a grant, a state or territory must enter into a partnership with nonprofits and similar organizations or tribal nations. These public-private partnerships must foster the use of technology platforms by providers and payors of health care and social services to improve cross-sector coordination. This includes developing funding models to make the platforms financially self-sufficient. HHS must consult with stakeholders to develop data standards and guidelines for these grants, and the Government Accountability Office must evaluate the impact of the grants.