What is the difference between federal and subject wages Employees earn gross wage which is total earnings but I need to figure subject wages which i believe are earnings after pre-tax deductions?

Well sort of - Each type of "subject income" is different and defined by the item and situation. So a gross income, being what most people consider their pay before taxes. Federal taxable income defines what is pay differently. sometimes in big ways (like the value of life insurance over a certain amount is pay, contributions to retirement account may not be, etc,), and sometimes the item is subject as pay on all the types..but at different times. Pay subject to FICA tax uses yet another definition and includes some things and excludes others that Federal taxable income does. We can go on with that for some while...and the items may be considered something in one work situation and not in another: For example, a place to live may be income for an employee in say NYC, but not one on an oil derrick in the North Sea. You need to find the definition of exactly what "subject" your addressing...and compare it to the other.