COS- F1 to H1 . Need help with W4

[mavsrules]

This is my background:

I am married with single job and non-working spouse on dependent visa and no children. These are our status details for the year 2011

F1/F2 (OPT) - Jan 1 - Sep30
H1/H4 - Oct 1 - Dec 31

On W4, I need help with point 3 - It states that I can claim as single if spouse is non-resident alien.

i) My Q is - Is she considered resident or non-resident alien for tax year 2011? because for the substantial presence test, she will be a US resident only for 182 days (Oct 1 - Dec 31). On F2 visa (until Sep30) she was considered a non-resident alien.

ii) What is the difference in filing Single vs married ?

Thanks
Sanjay

[kabkaba]

W4 is not a big deal. It just determines how much is withheld. It is always safer err on the higher side to that slightly more tax is withheld and you get a refund when you file a return.
I think you both will be non-resident for Federal tax purpose.