· National Emergency

· Failure of constitutional machinery in states

· Financial Emergency

Under Article 352 of the Indian Constitution, the president can declare such an emergency simply on the idea of a written request via the cabinet of ministers headed via the prime minister. Such a proclamation must be accepted by the parliament with at least two-thirds majority within one month.

War or External aggression approach an External Emergency, and an armed revolt means  Internal Emergency. As consistent with the Constitution’s forty-fourth amendment in 1978, the President can declare National Emergency in entire or in any part of India on grounds of revolt or outside aggression or inner disturbance. 

Also, National Emergency may be declared by President if any minister of cabinet rank headed by PM requests him to do that.