Your Social Security statement shows three numbers: an estimated benefit at 62, one at Full Retirement Age, and one at 70. What it does not show is the formula that produced them. That formula has always been public. Most workers who have paid into Social Security for decades have never seen it. Here is how it works.
The Social Security Administration (SSA) does not use the dollar amounts from your old pay stubs directly. It first adjusts your historical earnings upward to reflect how much wages in general have risen since you earned that money. This process is called wage indexing. For workers who become eligible in 2026, the SSA uses the 2024 national average wage index of $69,846.57 as its benchmark. Your earnings from each earlier year are multiplied by a ratio that compares that benchmark to the average wage in the year you earned the money. The research underlying this article puts a concrete number to that process: a worker who earned $50,000 in 2003 does not have $50,000 counted in the calculation. The SSA applies an index factor of approximately 2.05, bringing the adjusted value to roughly $102,500. Earnings from 2024 forward are counted at face value with no further adjustment. The intent is straightforward — to compare your earnings to the economic conditions of the present day rather than the year you earned them. The result is a calculation that more accurately reflects where your lifetime earnings fell relative to the broader workforce.
Once all indexed earnings are in hand, the SSA selects your 35 highest-earning years. Those adjusted figures are added together and divided by 420 — the number of months in 35 years — and rounded down to the nearest dollar. The result is called the Average Indexed Monthly Earnings, or AIME. This is where employment gaps create a structural disadvantage that the SSA does not announce. If a worker has fewer than 35 years of covered employment — work in a job that contributed to Social Security — the missing years are filled with zeros. Those zeros drag the AIME down. THE ZERO-YEAR EFFECT A worker who spent five years outside the workforce — to raise children, care for a parent, or recover from a health event — may have a measurably lower monthly benefit than a worker with an identical earnings history but no gaps. The SSA does not flag this. There is no letter, no warning. The zeros simply appear in the math. Workers who are approaching 35 years of covered earnings and can add one more year of substantial income may meaningfully increase their AIME — and their monthly benefit.
The AIME does not convert directly into a monthly benefit. It feeds into a second formula that applies different replacement rates to different segments of that monthly average. The thresholds between those segments are called bend points. For workers first eligible in 2026, the bend points are $1,286 and $7,749. The formula works as follows: AIME Segment (2026) Replacement Rate **Maximum Benefit from This Segment** First $1,286 90% $1,157.40 $1,287 to $7,749 32% $2,068.16 Above $7,749 15% Varies with total AIME The result — rounded down to the nearest dime — is called the Primary Insurance Amount, or PIA. The PIA is the monthly benefit paid to a worker who claims at their Full Retirement Age. For anyone born in 1960 or later, that age is 67.
The three-tier structure is intentional. It is designed to replace a higher share of pre-retirement income for workers who earned less during their careers. A worker whose AIME falls entirely within the first segment receives 90 cents for every dollar of average monthly earnings. A worker whose AIME extends deep into the third segment receives only 15 cents on the dollar for that portion. Two benchmarks from the underlying research illustrate the range. A worker who consistently hit the maximum taxable earnings ceiling — $184,500 in 2026 — would have an AIME of approximately $14,358 and a PIA of $4,216.90. A middle-income worker with an AIME of $5,825 would have a PIA of $2,609.80. > *High earners pay into Social Security on more income but receive a > lower replacement rate. Lower earners pay in on less — and get > proportionally more back.*
Pre-Retiree Tax-Aware
integrity: All figures sourced from SSA.gov primary documents.