Notch Fairness Act of 2021 This bill increases Social Security retirement benefits for certain individuals born between 1917 and 1921, referred to as the Notch years. Currently, these individuals receive lower cost-of-living increases than individuals born in 1916 or earlier, as a result of legislative changes to Social Security benefits enacted in 1977. Under the bill, eligible individuals may elect to (1) recompute and increase their current primary insurance amount according to a specified schedule, or (2) receive lump sum payments over four years totaling $5,000.