How much individual income tax do you need to withhold in a year in order not to be subject to penalties in the US?

== == It is based on percentages of what you will owe...which is essentially a percentage of what you will make annualized, and after considering your filing status, deductions and exemptions. But it's really easier than that. But it isn't an amount per se.

Generally, you should make estimated tax payments if you will owe tax more, than an amount specific by law, after withholding and credits, and the total amount of tax withheld and your credits will be less than the smaller of: # 90% of the tax to be shown on your current tax return, or # 100% of the tax shown on your prior year's tax return, if your prior year's tax return covered all 12 months of the year. However, if your prior year's adjusted gross income exceeded a certain amount based on your filing status, then you must pay 110% instead of 100% of last year's tax.

See link to a good document to figure it out, with work sheets to help.

THIS IS FOR FEDERAL ONLY...YOU NEED TO CONSIDER YOUR STATE AND CITY, IF THEY HAVE AN INCOME TAX.

http://www.irs.gov/publications/p505/index.html