SSA logo: link to Social Security Online home725. How does SSA compute the number of reduction months?

To compute the number of reduction months, we count all months, beginning with the first month of your entitlement to reduced benefits, up to the month in which you reach full retirement age.

For widow(er)'s insurance benefits that begin before age 60, the reduction formula in §724.3 requires using only months between age 60 and full retirement age.