Pandemic Relief for Working Seniors Act of 2021 This bill increases the amount of income that individuals who are younger than full retirement age may earn in taxable years 2020 and 2021 without reductions to their Old-Age, Survivors, and Disability Insurance (OASDI) benefits. Under current law, these individuals are subject to the retirement earnings test, which reduces their OASDI benefits if their earnings exceed an annual limit. This limit is set at $18,240 for 2020 and $18,960 for 2021 for most individuals. However, the limit for individuals who reach full retirement age in 2020 or 2021 is $48,600 or $50,520, respectively. This bill increases the applicable income limits to equal the amount of the contribution and benefit base. The contribution and benefit base serves as a cap on both the amount of earnings subject to the Social Security payroll tax and the amount of earnings used to calculate benefits. It is set at $137,700 for 2020 and $142,800 for 2021.