I am currently an F-1 student with OPT. I came to the US as an F-1 student since 2013, so 2018 is my 6th year. I also stayed for more than 183 days in the US in 2018, so I passed the substantial presence test. However, my first day in the US in 2018 was January 4th, 2018, so it seems like that I should be a non-resident alien from January 1st to 4th in 2018, and then a resident alien from January 4th to December 31st. In this case, should I file my 2018 tax as a resident alien or as a dual status? Thank you!
You start counting days present from the day you entered USA in 2018 --- you count your days absent from the USA as days absent i.e. towards substantial presence test. But it really does not make a substantial difference , because you will meet the substantial presence during the year 2018 and therefore you are resident for tax purposes for the year 2018, especially if you have had no substantial income from foreign sources during the first part of 2018 .
You start counting days present from the day you entered USA in 2018 --- you count your days absent from the USA as days absent i.e. towards substantial presence test. But it really does not make a substantial difference , because you will meet the substantial presence during the year 2018 and therefore you are resident for tax purposes for the year 2018, especially if you have had no substantial income from foreign sources during the first part of 2018 .