Metro Accountability and Investment Act This bill reauthorizes for FY2022-FY2031 authority for the Department of Transportation (DOT) to provide grants to the Washington Metropolitan Area Transit Authority (WMATA) to finance in part the capital and preventive maintenance projects included in its Capital Improvement Program. It conditions the availability of funds, in part, on the WMATA Board of Directors certifying to DOT that it has adopted and will keep certain resolutions in effect for the entire funding period, including (1) establishing an independent budget authority, procurement authority, and hiring authority for its Office of the General Inspector; (2) ensuring its Inspector General (IG) can obtain legal advice from a counsel reporting directly to the IG; (3) requiring the IG to submit recommendations for corrective action to the General Manager and the Board of Directors of WMATA; (4) requiring the IG to publish such recommendations on its website; (5) requiring the WMATA Board of Directors to provide written notification to Congress at least 30 days in advance of the removal of an IG; and (6) prohibiting the WMATA Board of Directors from removing its Inspector General without a 30-day written notification that documents specific reasons for removal, including an abuse of authority.