If I retire at any point after age 62, are the benefit reductions prorated by month?

Essentially, yes.

You can claim Social Security retirement benefits at any time after reaching 62 years of age. But you are not entitled to your full retirement benefit — 100 percent of the benefit calculated from your lifetime earnings history — until you reach full retirement age, or FRA.

Full retirement age is 66 and 6 months for people born in 1957, 66 and 8 months for those born in 1958 and rising two months each year until the age becomes 67 for those born in 1960 or later. Your benefit is reduced a fraction of a percent for each month before FRA that you filed, and the reduction is permanent.

So, if you retire at, say, age 62 and 6 months, your benefit is, in effect, prorated — you are credited for waiting six months after becoming eligible. If you were born in 1960, that works out to a 2.5-point bump: The benefit reduction is 30 percent at 62, 27.5 percent at 62 and 6 months.

The prorating effect can continue up to age 70. Past your FRA, you earn delayed retirement credits that boost your eventual benefit by 2/3 of 1 percent for each month you wait to claim Social Security, until you hit 70.

Keep in mind

This prorating works similarly for spousal benefits you receive on a husband's or wife's earnings record: They are reduced if taken before FRA, but by a lower percentage for each month past age 62 that you wait to claim them. But there are no delayed retirement credits for spouse benefits; they max out at full retirement age.