Poverty Measurement Improvement Act This bill requires the Bureau of the Census to determine income and poverty levels in the United States in a manner that accounts for the receipt of federal benefits. Specifically, beginning in FY2021, the bureau must collect, in addition to the data collected under the Annual Social and Economic Supplement to the Current Population Survey, data from administering agencies related to participation in any federal benefit program and the monetary or cash equivalent value of such benefit for an individual, where possible, and otherwise for resource units or households; the total amount of market income for individuals; the total amount of entitlement and other income for individuals; payment of income taxes and payroll taxes for individuals; total resource unit income; and total earned resource unit income. The bill requires each administering agency to make available to the bureau such data as the bureau shall require for the purpose of carrying out this bill. The bureau shall (1) submit to Congress, by January 1, 2023, a report detailing the implementation of this bill; and (2) for 2024 and subsequent years, adjust the poverty thresholds used for determining poverty rates by using the personal consumption expenditure price index (as published by the Bureau of Economic Analysis). The bill (1) establishes within the bureau the Commission on Valuation of Federal Benefits, and (2) requires the Government Accountability Office to periodically report to Congress regarding poverty rates and related measures.