If the amount of Social Security taxes withheld was too much because two W-2s (from two different companies) put together went over $7,347 (the maximum Social Security taxes to be withheld for one taxpayer in a year), then TurboTax will compute the excess amount and refund it to you automatically as a credit on line 71 on page 2 of the 1040.
Please see Tax Topic 608 at the IRS website.
