I have a question regarding filling up W4 form for my new employer. I am on H1B and My wife is on F1-OPT for now. She is working in IT firm and her H1B is in process and we are waiting for the decision from USCIS. She has been in US since Aug 2007 and I have been since Aug 2008.

Following are my concerns
For Personal Allowances Worksheet From A to H I just need to put 1 In A? Everything else is 0 or blank

For Marital status Single or married? Because Note says if you spouse is non resident alien Check Single. I am not sure if we are considered to be resident or non resident alien.

What would be beneficial for us MFJ or MFS?

Please let me know. Thanks in advance

Almost for sure you will be filing jointly. That being the case, MAKE SURE your wife's employer is NOT withholding FICA (Social Security and Medicare) taxes. As an F-1 student, she is EXEMPT from those taxes, but getting a refund from the IRS will be a BIG hassle for the upcoming tax year/ It CAN be done, but it is a long and involved process. Better that the employer refund the improperly-withheld FICA taxes.

That said, HER salary will be taxed at the tax rate of the LAST dollar you will make in 2012, which means she must OVER-withhold to compensate. Hence, YOU should claim MARRIED with ONE allowance and SHE should claim SINGLE with ONE allowance. That should ensure enough taxes are withheld to meet your joint tax obligation.

So I am considered as resident for tax purpose in US? And My wife too?

You are a resident alien; by filing jointly, your wife is considered to be a resident alien for income tax purposes, but she is STILL exempt from FICA taxes.