Social Security — Maximizing your benefit on a median income

Two workers earn the same $65,000 for their whole careers. One puts in 35 years and claims at 67. The other starts at 22, stops at 60, and claims as early as the law allows. The first collects around $2,400 a month. The second collects around $1,680. Same salary, same contribution rate, and a gap of roughly $720 a month that runs for the rest of their life.

Nothing about that gap is negotiated. It falls out of a formula almost nobody reads, and it is decided by two things you still control: how many years you record, and the age you file. This is what the formula actually rewards.

The 35 years that set your cheque

The Social Security Administration takes every year you paid Social Security tax, adjusts each one for national wage growth, and keeps your 35 highest. It adds them, divides by 420 months, and calls the result your Average Indexed Monthly Earnings. Years with no earnings count as zero — they do not get skipped.

Then the formula pays you in layers rather than at one flat rate:

The bend points are indexed every year, so treat those three numbers as the 2025 shape of the formula rather than a permanent figure. The shape is the point. A median earner gets 90 cents back on the first slice of their average, and a high earner's marginal dollar returns 15 cents. Social Security is a much better deal for you than for your boss, and the replacement rates show it: roughly 40% of pre-retirement income replaced at the median, closer to 25% at the top.

Now the part that costs money. Twenty-six years of work instead of 35 means nine zeros averaged in, and your average drops by about a quarter — your benefit drops by roughly the same. Two workers, same salary, one with a decade out of the paid workforce to raise children or care for a parent: the one with the gap is looking at something near $1,700 a month instead of $2,400. Over a twenty-year retirement that is around $170,000. Replacing a zero year with even $30,000 of part-time earnings is one of the best-paid hours of work available to anyone over 55.

Filing age moves the number by 76%

Your Full Retirement Age is 67 if you were born in 1960 or later. Filing before it cuts your benefit permanently; filing after it raises it permanently. Both adjustments are fixed percentages, not estimates, and they apply for life.

Two things surprise people here. The early-claiming reduction is not a straight line: it takes 5/9 of 1% off for each of the first 36 months before your Full Retirement Age and 5/12 of 1% for every month beyond that, which is why 62 costs 30% while 65 costs 13% rather than 17%. And there is no age-71 option. Delayed retirement credits stop accruing at 70, so filing at 72 buys you nothing you could not have had two years earlier.

Marriage changes the maths twice

In a married couple, the case for the higher earner waiting is stronger than any argument from their own longevity, and the reason is the survivor benefit. When one spouse dies, the survivor keeps the larger of the two benefits, not both. Waiting to 70 is effectively insurance bought for two lifetimes with one decision: file at 70 and die at 82, and the survivor collects $2,976 a month instead of $2,400, about $7,000 a year, inflation-adjusted, for as long as they live after that. A single person with no dependent spouse gets no part of that. "Always delay to 70" is bad advice for a large group of people, and this is why.

A spouse can collect up to 50% of the other spouse's amount at 67, but that 50% is a ceiling reached only at Full Retirement Age. Filing at 62 pays roughly 32.5%, and the reduction sticks.

The trap most people walk into is the rule that replaced file-and-suspend. If you are eligible for both your own benefit and a spousal one, filing for either counts as filing for both. The plan where the lower earner takes a small cheque early while the higher earner holds out for 70 no longer exists. One exception survived: a divorced spouse can claim on an ex's record without that counting against their own, provided the marriage lasted at least 10 years and they have not remarried. The ex is never notified.

A spouse who never worked outside the home can still qualify on the other's record, and the survivor benefit carries the deceased's delayed credits with it. If the higher earner waited until 70, the survivor collects $2,976 a month, the full enhanced amount, rather than the $2,400 that would have been payable at 67. File for survivor benefits before your own Full Retirement Age and the same money is cut instead, to as little as 71.5% at 60. Two retirements rest on one filing date.