Medicaid Integrity Act of 2013 - Amends title XIX (Medicaid) of the Social Security Act with respect to a state's option to use Medicaid managed care organizations and primary care case managers.

Requires a state, acting through the state medical assistance agency or another state entity, in order to receive federal medical assistance percentage (FMAP) payments for expenditures under a contract with a managed care entity, to contract with an independent auditor to conduct biannual financial and performance-compliance audits of the entity.

Directs the Secretary of Health and Human Services (HHS) to set uniform audit standards according to specified requirements.

Requires the state to document for the Secretary its response to deficiencies reported in such audits.

Requires contracts between the state and managed care entities to require the managed care entity to give the independent auditor access to all necessary information.

Establishes sanctions for misrepresentation or falsification of information.

Prescribes requirements a state must meet to be allowed to enter into an agreement with an actuary with respect to the state's administration of a contract with a managed care entity.