Hi Folks,
My wife is currently working as independent contractor on 1099, she started working since June 2011, before that she was not working . She has L2 based EAD. We Came into US first in Sep 2010.
I want to know does she need to prepay Tax for 2011 as she is on 1099 there is no withholding? If so how do I prepay and when I am suppose to pay?

Thank you in advance

Regards
Santhosh

Have a look here about how to pay estimated taxes:
http://www.irs.gov/businesses/small/article/0, id=110413,00.html

If you are an employee you also have the option to increase your withholdings to cover your wife's tax. You can do that by filling out a new W4 for your employer with the increased withholding (less exemptions or you can add a specific amount to be withheld in addition)
If you want to pay the quarterly estimated taxes, there are 2 dates left September 15th/January 15th 2012.
You would need to calculate how much taxes including SE taxes you would owe and pay for June-August on September 15th and for September-December in January.

You are also covered by a "safe harbor" which allows your wife to NOT pay estimated taxes for 2011, pay all taxes due when she files her taxes return (either jointly with you or separately) WITHOUT paying any under-withholding penalties.

This safe harbor is available only in the first year she works as a contractor. Starting in 2012, she MUST file Form 1040-ES and pay estimated tax on 15 April 2012, 15 June 2012, 15 September 2012 and 15 January 2013, or have you pay more taxes through withholding on your salary.

Either way, the withholding or payments must cover all tax liabilities minus $1,000. You can pay up to $1,000 when you file your return without paying under-withholding penalties.

Hi Atlanta Tax expert ,
Thank you for you reply, does it require for safe harbor that she was present in all 12 months in 2010 in US and was Resident?

No to both questions.