What are the federal income tax rates on a 401K early withdrawal?

What ever your marginal rate will after you have completed you income tax return correctly. Could be any where from the -0- % to the maximum 35% tax bracket amount.

Essentially constantly variable and dependent on many things. 2 people with the same job and salary rarely pay the same tax.

In the United States, taxes are not levied according to occupation. An architect's marginal income tax rate depends on his total taxable income and the form under which he is conducting his business.

35%.

Yes it is income, plus you will be assessed a penalty.