Your Social Security retirement benefit is not a percentage of your final salary, and it is not an account balance. It is the output of a formula that takes your highest 35 years of earnings, adjusts them for wage growth, averages them monthly, and then runs that average through three brackets that deliberately pay back a much higher share to lower earners than to higher ones.
Understanding the shape of that formula tells you something the annual statement does not: which additional working years would actually move your benefit, and which would barely register.
| Step | What happens | Why it matters to you |
|---|---|---|
| 1. Index earnings | Past wages are restated in today's wage terms | Old low-nominal years are worth more than they look |
| 2. Take the top 35 | Best 35 indexed years only | Year 36 replaces your worst year, not an empty slot |
| 3. Divide by 420 | 35 years × 12 months = AIME | A monthly average, not an annual one |
| 4. Apply three brackets | 90% / 32% / 15% of AIME slices | The first slice is worth nearly three times the second |
| 5. Adjust for claiming age | Reduce before FRA, increase after | Covered in its own section below |
The authoritative description is on the SSA's benefit computation page.
Step 1: your old earnings are not counted at face value
A $20,000 salary in 1990 was not a small salary. Social Security agrees: it indexes your historical earnings to national average wage growth, restating them in terms comparable to today's wages.
Indexing applies up to the year you turn 60. Earnings from age 60 onward enter at their actual nominal value.
The practical effect is that early-career years matter more than people assume when they see the raw numbers on their statement. The figure the formula uses is not the figure printed as what you earned.
Step 2: 35 years, and the zeros are real
The formula uses your highest 35 indexed years. Not your last 35, and not an average of everything you ever earned.
If you worked 30 years, the calculation does not average 30 years. It averages 35 — with five zeros filled in. This is the single most consequential mechanic in the whole system for anyone with an interrupted career, and it cuts both ways:
- If you have zeros, an additional working year replaces a $0 with a real number. That is the largest possible improvement one year can make.
- If you already have 35 solid years, an additional year only replaces your lowest remaining year. If this year's earnings barely exceed that year's indexed value, the benefit moves very little.
This is why "one more year of work" is a genuinely different decision for two people with identical salaries and different career shapes. Check your earnings record for gaps before assuming the extra year pays.
Step 3: AIME is a monthly figure
Total the top 35 indexed years, divide by 420 months. That is your Average Indexed Monthly Earnings.
Dividing by months rather than years catches people out — AIME looks small next to an annual salary because it is a monthly number, and it is an average across a whole career including early low-earning years, not a reflection of your peak.
Step 4: the three brackets, and why they are progressive
AIME is then split into three slices, and a different percentage is applied to each:
- 90% of the first slice
- 32% of the slice between the first and second bend points
- 15% of everything above the second bend point
Those three percentages are statutory and stable. The dollar boundaries between them — the bend points — change every single year, because they are indexed to national wage growth. They are set based on the year you turn 62.
For workers first eligible in 2026 — that is, turning 62 this year — the bend points are $1,286 and $7,749 per month, per the SSA's bend point table. If you turn 62 in a different year, your cohort's bend points differ; the three percentages never do. The 2027 values will be announced in late 2026.
The result is called your Primary Insurance Amount — the benefit you receive at full retirement age.
The progressivity is the part worth internalising. The first slice of AIME is replaced at 90 cents on the dollar; earnings above the second bend point at 15 cents. A high earner receives a larger benefit than a low earner, but a far smaller share of their prior income. Anyone planning retirement on a "Social Security will replace X% of my salary" assumption should check which slice their earnings actually sit in — the higher your income, the lower that percentage will be.
A worked example, using the 2026 bend points
Suppose a worker turning 62 in 2026 has top-35 indexed earnings totalling $2,100,000.
AIME = $2,100,000 ÷ 420 = $5,000 per month
Applying the 2026 bend points of $1,286 and $7,749:
| Slice | Amount | Rate | Contribution |
|---|---|---|---|
| Up to $1,286 | $1,286 | 90% | $1,157.40 |
| $1,286 to $5,000 | $3,714 | 32% | $1,188.48 |
| Above $7,749 | $0 | 15% | $0.00 |
Sum: $2,345.88, rounded down to the next lower dime → PIA of $2,345.80 per month at full retirement age.
Notice the shape: the first $1,286 of AIME contributes almost as much to the benefit as the next $3,714 combined. That is the progressivity doing its work — and this worker never even reaches the 15% slice.
Figures verified against the SSA bend point table, August 2026. A worker in a different eligibility year gets that year's bend points.
Step 5: claiming age changes the payment, not the PIA
The PIA is what you get at full retirement age — which is 67 for everyone born in 1960 or later. Claiming earlier or later adjusts the payment:
- Claiming before FRA reduces it permanently. At 62 with an FRA of 67, the reduction is 30% — the worker in the example above would receive about $1,642 instead of $2,345.80, for life. The reduction is not reversed at FRA.
- Claiming after FRA increases it by 8% per year of delay through delayed retirement credits, which stop accruing at age 70. Waiting from 67 to 70 lifts the payment to 124% of PIA — about $2,909 in the example. There is no benefit to delaying past 70.
The earliest claiming age for retirement benefits is 62. If you are still working while claiming, a separate earnings test applies — see working while collecting Social Security.
What actually moves your number
Ranked by leverage:
- Filling a zero year. Largest single-year effect available. Check your record for gaps first.
- Replacing a genuinely low year once you have 35. Effect depends entirely on the gap between this year and the year being displaced.
- Delaying the claim, up to 70. Predictable, and independent of your work record.
- An extra year at high earnings when you already have 35 strong years. Real, but often much smaller than people expect — those dollars may land in the 15% slice.
What to actually do
- Pull your earnings record from your my Social Security account and read it for gaps or missing years, not just the estimate at the bottom. Errors are correctable, and they are worth correcting.
- Count your years with real earnings. Under 35 changes the whole calculus of working longer.
- Do not plan on a replacement-rate rule of thumb. Find which slice your AIME sits in.
- Treat the SSA estimate as an estimate. It assumes you keep earning at your current rate until the age shown. If you plan to stop earlier, the real figure is lower.
- Decide the claiming age separately from the earnings question. They are independent levers.
This article explains the federal benefit formula in general terms and is not advice for your situation. The SSA's calculators run your actual earnings record, which no article can do.
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