Charity Care and Hospital Tax-Exempt Status Reform Act of 1991 - Amends the Internal Revenue Code to declare that an otherwise tax-exempt organization which operates a hospital shall not be exempt from tax unless the hospital: (1) has an open-door policy toward Medicare and Medicaid patients and serves in a nondiscriminatory manner a reasonable number of such patients; and (2) provides in a nondiscriminatory manner sufficient qualified charity care and sufficient qualified community benefits. Provides for determining the standards of such service. Sets forth special reporting requirements for such organizations. Provides for rewarding hospitals which consistently meet charitable requirements.

Establishes an excise tax for hospitals which fail to meet such requirements. Amends the Social Security Act to provide for the use of such excise tax payments under the Medicaid program.

Amends the Internal Revenue Code to require a hospital organization applying for tax-exempt status to include a statement from the appropriate State official on the hospital's compliance under this Act.