Hello,
I've been an F1 student since Fall 2007, and was a J1 scholar for 2006 until Spring 2007.
Until now, I have been filing taxes as a nonresident alien, as the substantial presence test does not apply if you can claim to be an exempt individual, which I can as I have been a student for less than 5 years and there is a tax treaty with my country (France).

My question is, do I have to claim that exemption, or can I choose not to claim it
And file as a resident (as I meet the substantial presence test)? It would be much more advantageous for me to file as a resident than a nonresident.

Thank you for any help.

No, you cannot "choose" to be a resident when your F or J visa stops you from being a resident, bsed on its time limitations.

Its part of tax law that these individuals are exempt from becoming a resident; as long as they are in substantial compliance with their visa terms.

There are circumstances in which you can choose to become a resident however, e.g. when you're married to a resident/US citizen, and you elect to file MFJ with them , or in the case where you can elect to be a resident for part of the year under the" first year choice" rule, where you meet the substantial presence test in the following year, (see pub 519 for details).

Hope this helps.