# Federal Medical Assistance Percentage The share of each state dollar that the federal government reimburses under [[Medicaid]] and a set of related programs. Under section 1905(b) of the Social Security Act the rate is 100 per centum less a state percentage, where the state percentage bears the same ratio to 45 per centum as the square of state per capita income bears to the square of national per capita income — with a floor of 50% and a ceiling of 83%. The Secretary of Health and Human Services must promulgate the rates between 1 October and 30 November each year, using the average per capita income for the three most recent calendar years for which satisfactory data are available from the [[Department of Commerce]], and each promulgation is then conclusive for four quarters. The same percentages set federal matching for the TANF Contingency Fund, child support collections, child care mandatory and matching funds, Title IV-E foster care maintenance, adoption assistance and kinship guardianship assistance; the enhanced CHIP rate is derived from them. Because the income figure is per capita, the count of people is a divisor rather than a measure of need — which is why a census undercount *lowers* a state's FMAP, and why the 50% floor exempts the states already at the minimum. See [[Census Formula Funding Flow]]. ## See also - [[Medicaid]] · [[Census Formula Funding Flow]] · [[Bureau of Economic Analysis]] · [[Population Estimates Program]] · [[Department of Commerce]]