The ex-officio Chairman of the Planning Commission of India is the Prime Minister. This means that the Prime Minister is the chairperson of the Planning Commission by default, without having to be elected or appointed to the position.

The Planning Commission was established in 1950 to help the government of India plan and coordinate its economic development. The Commission was headed by the Prime Minister, and it included a number of other members, including experts in economics, industry, and administration.

The Planning Commission was dissolved in 2014, and its functions were taken over by the National Institution for Transforming India (NITI Aayog). However, the Prime Minister is still the ex-officio Chairman of NITI Aayog.

There are a number of reasons why the Prime Minister is the ex-officio Chairman of the Planning Commission. First, the Prime Minister is the head of the government, and as such, he or she is responsible for the overall economic development of the country. Second, the Prime Minister has the experience and expertise necessary to lead the Planning Commission. Third, the Prime Minister is in a position to coordinate the work of the Planning Commission with other government departments.

The fact that the Prime Minister is the ex-officio Chairman of the Planning Commission gives the Commission a high degree of political authority. This is important because the Planning Commission is responsible for making recommendations on a wide range of economic policies, including those that have a significant impact on the private sector.

The ex-officio Chairmanship of the Planning Commission is a significant responsibility. The Prime Minister must be able to provide the Commission with the necessary political support, while also ensuring that the Commission's recommendations are based on sound economic principles.