There is no maximum for Medicare, but for Social Security, the maximum taxable wages is $118,500 (2016).
If it is the case that neither W-2 was over $118,500 for Social Security wages but was only in the aggregate, the TurboTax will detect that more than $7,347 (6.2% of $118,500) was withheld and return the excess to you as a tax payment on line 71 on page 2 of the 1040.
