Primary Insurance Amount and Monthly Benefit Amount calculations
Main article: Primary Insurance Amount
Workers in Social Security covered employment pay FICA (Federal Insurance Contributions Act) or SECA (Self Employed Contributions Act) taxes and earn quarters of coverage if earnings are above minimum amounts specified in the law. Workers with 40 quarters of coverage (QC) are "fully insured" and eligible for retirement benefits. Retirement benefit amounts depend upon the average of the person's highest 35 years of "adjusted" or "indexed" earnings. A person's payroll-taxable earnings from earlier years are adjusted for economy-wide wage growth, using the national average wage index (AWI), and then averaged. If the worker has fewer than 35 years of covered earnings these non-contributory years are assigned zero earnings. The sum of the highest 35 years of adjusted or indexed earnings divided by 420 (35 years times 12 months per year) produces a person's Average Indexed Monthly Earnings or AIME.

The AIME is then used to calculate the Primary Insurance Amount or PIA. For workers who turn 62 in 2021, the PIA computation formula is:

(a) 90 percent of the first $996 of average indexed monthly earnings, plus

(b) 32 percent of average indexed monthly earnings between $996 and $6,002, plus

(c) 15 percent of average indexed monthly earnings over $6,002

For workers who turn 62 in the future, the 90, 32, and 15 percent factors in the computation formula will remain the same but the dollar amounts in the formula (called bend points) will increase by wage growth in the national economy, as measured by the AWI. Because the AIME and the PIA calculation incorporate the AWI, Social Security benefits are said to be wage indexed. Because wages typically grow faster than prices, the PIAs for workers turning 62 in the future will tend to be higher in real terms but similar relative to average earnings in the economy at the time age 62 is attained.

Monthly benefit amounts are based on the PIA. Once the PIA is computed, it is indexed for price inflation over time. Thus, Social Security monthly benefit amounts retain their purchasing power throughout a person's retirement years.

A worker who first starts receiving a retirement benefit at the full retirement age receives a monthly benefit amount equal to 100 percent of the PIA. A worker who claims the retirement benefit before the full retirement age receives a reduced monthly benefit amount and a worker who claims at an age after the full retirement age (up to age 70) receives an increased monthly amount.

The 90, 32, and 15 percent factors in the PIA computation lead to higher replacement rates for persons with lower career earnings. For example, a retired individual whose average earnings are below the first bend point can receive a monthly benefit at the full retirement age that equals 90 percent of the person's average monthly earnings before retirement. The table shows replacement rates for workers who turned 62 in 2013.

The PIA computation formula for disabled workers parallels that for retired workers except the AIME is based on fewer years to reflect disablement before age 62. The monthly benefit amount of a disabled worker is 100 percent of PIA.

Benefits for spouses, children, and widow(er)s depend on the PIAs of a spouse or a deceased spouse. Aged spouse and divorced spouse beneficiaries can receive up to 50 percent of the PIA. Survivor benefit rates are higher and aged widow(er)s and aged surviving divorced spouses can receive 100 percent of the PIA.

Federal, state and local employees who have elected (when they could) NOT to pay FICA taxes are eligible for a reduced FICA benefits and full Medicare coverage if they have more than forty quarters of qualifying Social Security covered work. To minimize the Social Security payments to those who have not contributed to FICA for 35+ years and are eligible for federal, state and local benefits, which are usually more generous, Congress passed the Windfall Elimination Provision, WEP. The WEP provision will not eliminate all Social Security or Medicare eligibility if the worker has 40 quarters of qualifying income, but calculates the benefit payments by reducing the 90% multiplier in the first PIA bendpoint to 40–85% depending on the number of Years of Coverage. Foreign pensions are subject to WEP.

A special minimum benefit, based on an alternative PIA calculation, is available for some workers with long careers but low earnings. However, it is rarely higher than the regularly-computed PIA and thus few workers qualify for the special minimum benefit. Only 32,000 individuals received the special minimum benefit in 2019.

The benefits someone is eligible for are potentially so complicated that potential retirees should consult the Social Security Administration directly for advice. Many questions are addressed and at least partially answered on many online publications and online calculators.
Based on the reference text, provide a summary of how the monthly benefit amount for social security is calculated.
The monthly benefit amount for social security is calculated by determining an individual's highest 35 years of "indexed" earnings. The sum of the highest 35 years of "indexed" earnings is divided by 420, which is the number of months in 35 years, to determine an individuals Average Indexed Monthly Earnings, which is referred to as AIME. Once an individuals AIME is determined, the formula to calculate the monthly benefit is as follows:
- 90 percent of the first $996 of AIME, plus
- 32 percent of AIME between $996 and $6,002, plus
- 15 percent of AIME over $6,002