How can I determine how much will be taken out of my pay for taxes?

Social Security (6.2%) and Medicare (1.45%) are flat taxes withheld at the percenteages noted. There is currently a cap of $104,000 on the Social Security portion. After the $104K threshold is met, no more Social Security taxes are withheld.

There is NO CAP on Medicare taxes, and, it should be noted, that one of Barack Obama's proposals is to dramatically raise the cap for Social ecurity withholding.

State income tax withhold depends on the individual state.

Federal withholding depends on a variety of factors, but the prinpal drivers are your marital status and the number of exemptions you select on the W-4: the more exemptions claimed, the less money withheld.