Somewhere in the Social Security Administration’s records is a year-by-year ledger of everything you have ever earned on the books, and when you retire, exactly 35 of those years will decide the size of your check. Not your last salary, not your best year, not some average of your whole career: your 35 highest years, adjusted for the growth of national wages, fed through a three-bracket formula.
Understanding that machinery is worth real money, because several of the levers, which years count, whether zeros sit in your record, when your earnings stop, are still in your control late in a career. Here is the computation, step by step, using the Social Security Administration’s own published formula.
Step one: your earnings get indexed
Old wages are not compared to new wages at face value. A $20,000 salary in 1990 represented a much bigger slice of the era’s typical paycheck than $20,000 does today, so SSA scales each year of your earnings up by the growth in the national average wage between that year and the year you turned 60. The multipliers come from the average wage index series, which SSA publishes annually. Earnings after age 60 get no adjustment and count at face value, which is one reason strong earning years in your early sixties can still muscle their way into your top 35.
Only earnings up to each year’s taxable maximum count, since that is all you paid Social Security tax on. Earnings that never had Social Security tax withheld, from some government jobs, for example, do not appear at all.
Step two: the best 35 years get averaged
From the indexed ledger, SSA takes the 35 highest years, adds them up, and divides by 420, the number of months in 35 years. The result is your average indexed monthly earnings, or AIME, the single number the benefit formula runs on. SSA describes the computation in its benefit calculation examples.
The 35-year window is where careers show their scars. Work fewer than 35 years and the missing years enter the average as zeros, dragging the AIME down. A worker with 30 earning years and five zeros is averaging their career over 35 years anyway. The flip side is the quiet payoff of working a little longer: each additional decent year replaces a zero, or a thin early-career year, in the top 35. For someone with gaps in their record, a few more working years can raise the eventual benefit meaningfully, and the gain compounds over every retirement check that follows.
Step three: the bend point formula
The AIME then passes through a formula that is deliberately tilted toward lower earners. For workers first eligible in 2026, meaning those turning 62 this year, the primary insurance amount formula pays 90 percent of the first $1,286 of AIME, 32 percent of the amount between $1,286 and $7,749, and 15 percent of anything above $7,749.
Those two dollar thresholds are the bend points, updated every year with national wage growth; SSA publishes the full history in its bend point table. The year that matters for you is the year you turn 62; your bend points lock in then, no matter when you actually claim.
A worked example: an AIME of $6,000 produces 90 percent of $1,286, which is $1,157.40, plus 32 percent of the remaining $4,714, which is $1,508.48. The sum, $2,665.88, rounds down to the next lower dime: a primary insurance amount of $2,665.80 per month. Notice the tiering in action: the first slice of earnings was replaced at 90 cents on the dollar, the rest at 32. A high earner’s dollars above the second bend point earn only 15 cents each, which is the system’s progressivity written in arithmetic.
Step four: your claiming age adjusts the result
The primary insurance amount is what you receive by claiming at your full retirement age, 67 for anyone born in 1960 or later. Claim earlier, as young as 62, and the check is permanently reduced; wait past full retirement age and delayed retirement credits increase it until 70. Cost-of-living adjustments then ratchet the benefit each year you receive it. But every one of those adjustments is a percentage applied to the number the 35-year math produced, which is why the earnings record underneath is the foundation of everything.
What to check while you can still fix it
The formula only works on the earnings actually recorded, and errors happen: employers misreport, names change after marriage, a year of freelance income gets filed under a mistyped Social Security number. Open a my Social Security account at ssa.gov/myaccount and read your earnings record year by year against your own tax returns or W-2s. A missing high-earning year silently swaps a zero or a weak year into your top 35, and corrections are far easier to make while the paperwork proving your wages still exists.
While you are there, look at the estimate with clear eyes: it assumes you keep earning at your recent level until you claim. If you are considering retiring at 58, or shifting to part-time, your real top-35 average will differ from the projection. The formula is fixed and public. The inputs, for a few more years at least, are yours.
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