You are considered an Indian resident for a financial year:
i. If you are in India for at least 6 months (182 days) during the financial year
ii. You are in India for 2 months (60 days) in the previous year and have lived for one whole year (365 days) in the last four years
If you are an Indian citizen working abroad or a member of a crew on an Indian ship, only the first condition is available to you – which mean you, are a resident when you spend at least 182 days in India. The same is applicable to a Person of Indian Origin (PIO) who is on a visit to India. The second condition is not applicable to these individuals. A PIO is a person whose parents or any of his grandparents were born in undivided India.

You are an NRI if you do not meet any of the above conditions.