How Social Security benefits work

Social Security retirement benefits do not use the final salary or a simple average of paychecks. The calculation begins with earnings on which Social Security tax was paid, called covered earnings. Earlier covered earnings are wage-indexed so that an old salary is compared with the general wage level nearer retirement rather than taken at its face amount.

The highest 35 years are selected. If the record contains fewer than 35 years, zero years fill the missing slots. The indexed earnings are added and spread across the months in those years to produce average indexed monthly earnings, or AIME. Earnings after the indexing age still enter the record at their nominal amount and can replace a lower year.

That first stage explains why one more working year can have two very different effects. If it replaces a zero or a low year, AIME can rise. If all 35 selected years are already higher, the new year changes nothing. The payroll tax feeding the covered record is explained in how FICA works.

AIME is not the benefit. It is the earnings base passed into a progressive formula. The result of that second stage is the primary insurance amount, or PIA, which is the monthly benchmark payable at full retirement age before later adjustments.

The PIA formula divides AIME into slices. For a worker whose eligibility year is 2026, the first bend point is $1,286 and the second is $7,749. The raw formula is:

$$\text{PIA}_{raw} = 0.90\min(A,1286) + 0.32\min(\max(A-1286,0),7749-1286) + 0.15\max(A-7749,0)$$

$A$ is AIME. The first slice is replaced at 90 percent, the next at 32 percent and the final slice at 15 percent. The formula is marginal: crossing a bend point changes the percentage on only the dollars above that point. It does not reprice all earlier AIME at the lower percentage.

At an AIME of $5,000, the first slice contributes $1,157.40 and the next contributes $1,188.48. The third slice is 0. Raw PIA is $2,345.88. Social Security floors that result to the next lower dime, producing $2,345.80.

Bend points are indexed by national wage growth and belong to the year a worker first becomes eligible, usually the year the worker turns 62. They do not switch to a later year's bend points merely because the worker waits to claim. That locks the formula's thresholds to an eligibility cohort while later cost-of-living adjustments update the resulting benefit.

PIA is the monthly retirement benefit at full retirement age before deductions and family adjustments. Full retirement age depends on birth year. For workers whose full retirement age is 67, claiming at 62 reduces the worker benefit by about 30 percent, while waiting until 70 raises it by about 24 percent through delayed retirement credits.

Those percentages apply to the worker's PIA, not to AIME. The early reduction is actuarial and permanent for that claim, apart from later cost-of-living adjustments. Delayed retirement credits stop at age 70, so waiting beyond that age does not add another delayed credit.

The adjustment is not a statement about the best age to claim. Claiming sooner pays a smaller amount for more months. Claiming later pays a larger amount for fewer expected months. Health, work, survivor protection, taxes and other income determine which stream a household is comparing.

A benefit quoted in future nominal units can rise while its purchasing power stands still. Annual cost-of-living adjustments are intended to track inflation after entitlement. The distinction between a nominal change and what it buys is covered by the real rate definition and the safe withdrawal rates guide.

The worker benefit is only one claim that can sit on an earnings record. A spouse may qualify for a spousal benefit tied to the worker's PIA. A surviving spouse may qualify under survivor rules tied to what the worker was receiving or entitled to receive. Divorced spouses can qualify when the marriage and other conditions meet the statutory tests.

These amounts do not simply stack. Social Security generally pays a person's own benefit first, then adds enough from another record to reach the higher amount for which that person qualifies. The family maximum can also limit benefits paid to several family members on one record. Survivor benefits use their own claiming ages and reduction schedule rather than copying the retirement-benefit schedule.

That structure is why the PIA remains useful even when the worker waits to claim. Spousal calculations begin from PIA, while survivor protection can reflect delayed retirement credits. The claiming decision can therefore change the stream left to a surviving spouse as well as the worker's own stream.

Eligibility and family status select the rule before any arithmetic is run. The two examples here calculate only the retired worker's PIA from AIME.

PIA is a gross benchmark. The amount deposited can differ after several separate adjustments. Cost-of-living adjustments update the entitled amount. Medicare premiums can be deducted. Federal income tax withholding can be elected, and part of the benefit can become taxable when combined income crosses the applicable thresholds.

Work before full retirement age can also trigger the retirement earnings test. Benefits withheld under that test are not simply lost: the agency later adjusts the benefit at full retirement age to account for months withheld. The earnings test concerns wages and self-employment income, not every source of household cash.

The funding flow is separate from the benefit formula. Current payroll taxes largely pay current benefits through trust funds. A person's payroll contributions do not sit in an individual investment account bearing that person's name. The paycheck calculator shows the Social Security tax line on current pay. The PIA formula converts the covered earnings record into an insurance benefit.

An official earnings record is therefore the useful input to a personal estimate. It shows which years are present and whether wages were credited correctly before the claiming adjustment is applied.

Both examples use the bend points for workers first eligible in 2026: $1,286 and $7,749. The first runs $5,000 of AIME through two slices and floors the raw $2,345.88 result to $2,345.80. The second runs $8,000 through all three slices and floors $3,263.21 to $3,263.20.

The examples isolate the PIA formula. Claiming age then adjusts that benchmark, and family benefits, cost-of-living adjustments, the earnings test, tax withholding and Medicare deductions sit around it. A current Social Security statement supplies the earnings record and agency estimate for an individual claim.

This explanation and its calculations are educational material, not financial advice.