On which assessee does income tax imposed?
 

Tax assessee may be resident or non-resident. Residents are further subdivided into two sub-categories
Resident and ordinarily resident, and
Resident but not ordinarily resident.
To determine which category you fall into, apply the following tests to the tax year from April 1 to March 31.

Resident

A Resident is one who falls into either of these two categories:
Is in India for 182 days in the year or more, or
In the preceding four years was in India for 365 days or more, and in the current tax year is in India for a total of 60 days or more
This applies to citizens of any nationality. However the period of 60 days in the second clause above will be extended to 182 days for those who fall into one of these two categories:
An Indian citizen who left India in any year for employment outside India, or
An Indian citizen or a foreign citizen of Indian origin (NRI), who is outside India, comes on a visit to India