Your Tier 1 taxes should 7.65% of your compensation, The maximum wages Social Security tax portion (6.2%) is 137,700. There is no maximum on the Medicare portion (1.45%). The Tier II tax is 4.9% with maximum wage amount of 102,300. You might be able to back into the amount of your taxable compensation by using the Tier I percentages. From there you can look reported wages on your W-2 and box 12 and box 14 come to a total that will equal the calculated amount. The only variable would be if your compensation is over 137,700. Otherwise you can divide your Tier I taxes by 7.65% to get to your taxable compensation amount then go from there.
