The Medicaid Integrity Improvement Act requires state Medicaid fraud control units to conduct annual audits of high-risk healthcare providers and suppliers starting within one year of the bill's enactment. These audits aim to identify potential fraud, waste, and abuse by examining a statistically valid sample of providers flagged as high-risk based on factors like abnormal billing patterns, prior audit history, payment irregularities, ownership changes, or fraud allegations. States must report annually to the federal government on the results of these audits, including how much money in overpayments was identified and collected. The bill allows the federal Health and Human Services Secretary to waive the audit requirement if a state submits an acceptable corrective action plan. This legislation affects state Medicaid programs and the healthcare providers they pay, with the goal of reducing improper payments and strengthening oversight of Medicaid spending.