My wife just accepted a new job and will be making 115k a year. I stopped working to go back to school full time. We have 1 child. My question is what should my wife claim on her w4? My biggest concern is that I don't want to owe anything come tax season.

If you are NOT working, she should file Form w-4 as MARRIED with THREE allowances. That should result in a small refund for you as a family.

If she folliows the directions on the W-4 form she will probably end up at 4 allowances (one for her, one for you, one for the child, and one for married filing jointly). If you have substantial child care expenses she may be able to claim 5, but for the first year it's probably advisable to leave it at 4 and see what happens. Then next year she can resubmit an updated form if necessary.

I would normally have advised FOUR allowances, but the OP seemed determined NOT to have to write a check come April 2013, which is why I went with THREE allowances, given the fact that we do NOT know if either HE was working at all in 2012 or if SHE was working prior to this job offer.

Offering advice in a vacuum of complete knowledge is always a risky proposition, so I erred on the side of caution.