I lived in New Mexico from January to August 18. I moved to New York on August 18. I know I have to pay taxes to both states and already filed in NM, but am confused about the forms necessary. It seems the NY state wants to tax me for income earned in NM. Am I wrong? Also, New Mexico had a great system to prepare and file state taxes online for free, does NY?

For NY you are part year resident and must report income earned while in NY.

For NM you may be considered resident, if yes, you will report your worldwide income for 2008 including NY income. You will also claim credit for taxes paid to NY. Your U.S. Tax Return: Working or Living in Two or More states