Form 1040NR I believe, but this is a tax question, not an immigration question.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.
Foreign nationals typically use form 1040NR, but you can check with tax professionals or a tax attorney. I believe that tax professionals charge a premium to taxpayers with a 1040NR because they are not typical and require additional work by the professional. It may be cheaper to purchase a tax return preparation software and do it yourself. However, that's a personal decision.
If you have additional questions, you can always contact a lawyer directly, whether myself or one of my colleagues. If you appreciate the time spent preparing this answer, kindly consider marking it BEST ANSWER or HELPFUL. Good luck to you.
Dean P. Murray
The Murray Law Firm
560 Sylvan Avenue
Englewood Cliffs, NJ 07632
Mr. Murray's response is NOT legal advice and does NOT create an attorney-client relationship. You should NOT rely on this response. Mr. Murray's response was generated without conducting a full inquiry as would occur during a face to face attorney-client consultation. It is likely that the response above may be made less accurate, or become entirely inaccurate, as you, i.e. the questioner, disclose additional facts that should only be discussed during a private consultation with an attorney. I strongly recommend that you consult an attorney who is licensed to practice law in your state (or, in the case of immigration law, and attorney in ANY state), whereupon all relevant facts will be discussed. All responses posted by Mr. Murray on Avvo.com are intended as general information for the education of the public, and not for any specific individual.
"Residency" for tax purposes is different from residency for immigration purposes. Even undocumented aliens who have no legal immigration status are expected to file the federal income tax returns if they have taxable income.
Given that you have lived in the US the last five years, you use the same tax forms that US citizens and LPRs use. The main tax forms are the 1040EZ, 1040A, and 1040. Which one you use depends on your facts.
You should be getting the same information returns (such as the W-2s) as other taxpayers.