Are social security and medicare calculated after personal deductions etc, or only on gross income?

Question

Trying to figure out my estimated federal taxes but a program I am using calculates my SS and Medicare higher than I predicted. Should I not have applied my personal deductions before figuring out these numbers?

Answer 1

Healthcare if often pre-fica/mc.  Subtract that out and see if that works the way you expect it to.

Answer 2

SS and Medicare are calculated on "after-tax income", which is gross income less some deductions, such as health care.

If you use paycheckcity.com, look through the options for type of income to see which is which.  Some income is "after-tax" for some purposes and "pre-tax" for others.

Answer 3

Gross Income.

Answer 4

If you are an employee without pretax benefits, your Social Security and Medicare are a flat 7.65% of your gross wages.  

Normally your employer should be sending in your share of SS and Medicare.  However you can send it in yourself and attach Form 8919 to your tax return to figure your uncollected Social Security and Medicare tax on wages.