Latest amount & definition
The "old-law" contribution and benefit base for 2015 is \$88,200. This is the base that would have been effective without the enactment of the 1977 amendments to the Social Security Act. The present-law contribution and benefit base is substantially higher than the old-law base.

Purpose of the old-law base
The old-law contribution and benefit base is used by:

• the Railroad Retirement program to determine certain tax liabilities and tier II benefits payable under that program to supplement the tier I payments which correspond to basic Social Security benefits,
• the Pension Benefit Guaranty Corporation to determine the maximum amount of pension guaranteed under the Employee Retirement Income Security Act,
• Social Security to determine a year of coverage in computing the special minimum benefit, and
• Social Security to determine a year of coverage (acquired whenever earnings equal or exceed 25 percent of the old-law base for this purpose only) in computing benefits for persons who are also eligible to receive pensions based on non-covered employment.

Determination of the old-law contribution and benefit base for 2015
The formula for determining the old-law contribution and benefit base is set by law. The formula is applicable only if a cost-of-living increase becomes effective for December of the year in which a determination of the base would ordinarily be made. Because there is a cost-of-living increase for December 2014, the formula is applicable. According to the formula, the old-law contribution and benefit base for 2015 is determined to be the 1994 old-law base (\$45,000) multiplied by the ratio of the national average wage index for 2013 to that for 1992, or, if larger, the 2014 old-law base (\$87,000). If the amount so determined is not a multiple of \$300, it is rounded to the nearest multiple of \$300.

Amounts informula Computation 1994 old-law base \$45,000 1992 average wage index 22,935.42 2013 average wage index 44,888.16 \$45,000 times 44,888.16 divided by 22,935.42 equals \$88,071.95, which rounds to \$88,200 \$88,200 exceeds the 2014 old-law base, so the old-law base for 2015 is \$88,200