I have been in the US since 1st of August 2016. I filed my taxes for the year 2017 as a non resident alien just now. In a tax workshop in the University I work and study I was told that as a F1 I have to file as non resident alien for 5 years. But I thought I should be able to file as a resident alien from 2018 onwards based on how the days are counted to determine the classification. Any help is appreciated
Counting the number of days is the Substantial Presence Test, where you are a resident alien for a given year if (the number of days you were present in the US that year + 1/3 the number of days you were present in the US the previous year + 1/6 the number of days you were present in the US the year before that) > 183 days. If you counted all your days in the US, you would already have been a resident alien for 2017.
However, they are correct, because as a student, you are an exempt individual (your days as a student are not counted in the Substantial Presence Test) unless you have been an exempt individual for any part of 5 previous calendar years. Basically, if you haven't been to the US in F or J status before, this makes you a nonresident alien for your first 5 calendar years in F1 status. (So, if you came during 2013 or before, you are a resident alien for 2018; if you came during 2014 or after, you are a nonresident alien for 2018.)