The Federal Insurance Contributions Act (FICA) tax includes two separate taxes. One is the social security tax and the other is the Medicare tax. Different rates apply for each of these. Only the social security tax has a wage base limit. The wage base limit is the maximum wage that is subject to the tax for the year.

If you worked for two or more employers during the year and your total wages exceeded the maximum amount for that year, too much social security tax may have been withheld from your pay. You can claim the excess as a credit on the current year tax return. You must file Form 1040 (PDF) or Form 1040A (PDF) to claim this credit.

For more information, refer to Publication 505, Tax Withholding and Estimated Tax.