Difference between NRI, OCI and PIO:

Difference between NRI, OCI and PIO: 

A Non-Resident Indian (NRI) is a citizen of India who holds an Indian passport and has temporarily emigrated to another country for six months or more for work, residence or any other purpose. 

Strictly speaking, the term "non-resident" is an economic concept and refers only to the tax status of an person who, as per section 6 of the Income-tax Act of 1961, has not resided in India for a specified period for the purposes of the Income Tax Act. The rates of income tax are different for persons who are "resident in India" and for NRIs. For the purposes of the Income-tax Act, "residence in India" requires stay in India of at least 182 days in a calendar year or 365 days spread out over four consecutive years. According to the act, any Indian citizen who does not meet the criteria as a "resident of India" is a non-resident of India and is treated as NRI for paying income tax. 
This implies that-Person Resident in India for less than 182 days during the course of preceding financial year and has gone out of India or who stays outside India, in either case:

a) for or on taking up employment outside India; or
b) for carrying on outside India a business or vocation outside India; or
c) for any other purpose, in such circumstances as would indicate his intention to stay outside India for a uncertain period.

A Person of Indian Origin (PIO) is a citizen of any other country but whose ancestors were Indian nationals at least four generations away. A PIO card is issued to PIOs other than Bangladeshi and Pakistani nationals with Indian origins, holding a foreign passport. The government issues a PIO Card to a Person of Indian Origin after verification of his or her origin or ancestry and this card entitles a PIO to enter India without a visa. Spouse of a PIO can also be issued a PIO card though the spouse might not be a PIO. This latter category includes foreign spouses of Indian nationals, regardless of ethnic origin, as long as they were not born in, or ever nationals of, the aforementioned prohibited countries. PIO Cards exempt holders from many restrictions that apply to foreign nationals, such as visa and work permit requirements, along with certain other economic limitations. PIOs can acquire non-agricultural and plantation property in India; can admit children to all educational institutes in India under NRI quota and can apply for various housing schemes of LIC, state governments and other government agencies. They are also exempted from registration at Foreigners Registration office at District Headquarters if stay in India does not exceed 180 days.

The PIO card can be withdrawn under following circumstances:

a) the PIO card was obtained through fraud, concealment of facts or false representation;
b) the activities of the card holder in India do not conform to the laws of the country and the Indian Constitution;
c) the card holder happens to be citizen of a country with which India is at war, or is supporting another country in acts of aggression against India;
d) the PIO has been found guilty of acts of terrorism, smuggling of arms and ammunition and narcotics;
e) has been sentenced in India up to one year's imprisonment or fined up to Rs.10,000;
f) the card holder's presence in India is detrimental to the interests of the country.

Overseas Citizenship of India (OCI) is provided to a foreign national, who was eligible to become a citizen of India on 26.01.1950 or was a citizen of India on or at anytime after 26.01.1950 or belonged to a territory that became part of India after 15.08.1947. His/her children and grand children are also eligible for registration as an Overseas Citizen of India (OCI). Minor children of such person are also eligible for OCI. However, if the applicant had ever been a citizen of Pakistan or Bangladesh, he/she will not be eligible for OCI.

Following benefits will be given to an OCI:

(a) Multi-purpose, multiple entry, lifelong visa for visiting India.
(b) Exemption from registration with local police authority for any length of stay in India.
(c) Parity with NRIs in respect of economic, financial and education fields except in matters relating to the acquisition of agricultural/plantation properties.