I arrived to US a month ago, on May 1st, because of a new work. I have been told by the company to fill W-4 form in. But, it seems that W-4 form must be filled in differently depending on my current status (resident alien or nonresident alien).

The rules to decide which is my status are here: http://www.irs.gov/publications/p519/ch01.html

Basically, it seems I need to pass the substantial presence test (see previous link) to determine whether I am a resident alien or not. At this moment, I definitely do not meet the substantial presence test, since I just arrived to US.

I understand, however, that I will need to file my first tax return on April 2017, and my fiscal year will end on December 2016. At that moment, I believe I will actually meet the substantial presence test.

I also have a spouse that is coming to US (with H4 visa) before July 1st which will also match the criteria for the substantial presence test at that time.

My question is: should I decide if I am a resident alien or not based on the date that I start working, or based on the date I will file my tax return? Can I fill as married, since we will both be resident aliens at that time?