Automatic Determinations
Contribution & Benefit Base
Wageindexed Amounts 
Method for determining the base
The formula for determining the OASDI contribution and benefit base
is set by law. The formula is applicable only if a
costofliving increase becomes
effective for December of the year in which a determination of
the base would ordinarily be made. Because there is a costofliving increase for December 2017, the
formula is applicable. The formula states that the base for any year
Y after 1994 is equal to the 1994 base of $60,600 multiplied by
the ratio of the national average wage index for
year (Y2) to that for 1992, with the result rounded to the nearest
multiple of $300. If the result is less than the current base, the base
is not reduced.
Base for 2018
Under the above formula, the base for 2018 shall be the 1994 base of $60,600
multiplied by the ratio of the national average wage index for 2016 to that for
1992, or, if larger, the 2017 base of $127,200. If the amount so determined
is not a multiple of $300, it is rounded to the nearest multiple of $300.
Calculation details
Amounts in formula 
1994 base  $60,600 
1992 average wage index  22,935.42 
2016 average wage index  48,664.73 
Computation  $60,600 times 48,664.73 divided by
22,935.42 equals $128,582.02, which rounds to $128,700 
Higher amount  $128,700 exceeds the base for 2017,
so the base for 2018 is $128,700 
