Maximizing America's Prosperity Act of 2021 This bill establishes annual spending limits that are equal to specified percentages of potential gross domestic product (GDP). Potential GDP generally refers to the GDP that would occur if the economy were at full employment without inflation. The spending limits apply to all budget authority and outlays of the federal government excluding net interest. The bill establishes procedures for enforcing the spending limits, including requirements for sequestration (i.e., automatic spending cuts) and for the President's budget and congressional budget resolutions to comply with the limits. The bill also requires at least 1% of total discretionary spending for each year to be reserved for emergencies.