Don't deduct Social Security taxes, but ...
You lose a lot of income each payday to Federal Insurance Contributions Act, or FICA taxes, the money withheld from your checks to pay for your future Social Security benefits. The debate as to whether Social Security will be around when you retire is still raging. But one thing is sure: Don't even think about trying to deduct these taxes.
But if you overpaid this tax, you can get a credit for your Social Security overwithholding. There is a limit on how much FICA taxes can be contributed each year. The tax is withheld on up to the Social Security earnings base, which is adjusted annually for inflation. For 2014, it's $117,000; for 2015, it's $118,500.
If you had multiple jobs and your combined earnings exceeded the wage base, you probably had too much FICA withheld. You can claim the excess Social Security tax as a credit when you file your tax return.