A person who is not a member of the legislative assembly can become a CM if he gets elected to the State Legislature within six months.
"It is for the party to decide, but it is not necessary a sitting MLA will become the Chief Minister.... when Mamata Ji became Chief Minister, she was not an MLA", Ghosh told Press Trust of India (PTI).
There is a legislature for every state, which consists of a Governor and one House or two Houses- legislative council and legislative assembly. The Governor appoints the Chief Minister through a majority in the state legislative assembly.
According to Indian Constitution, a person is eligible for a chief minister's post, provided he/she is a citizen of the country, is of at least 25 years of age, and is a member of the legislative assembly.
However, according to the Article 164(4) of the Indian Constitution, an individual who is not a member of the legislature can also be considered as the chief minister, provided he/she is elected to the State Legislature within six months from the date of their appointment. Failing this, the individual will no longer hold the post.
For example, On December 7, 1960, Chandra Bhan Gupta was appointed as the Chief Minister of Uttar Pradesh by the Governor when he was not a member of the assembly. However, he was nominated to the council within less than two months from his appointment as a CM, the Bar and Bench reported.
Though a non-member can indeed become a Chief Minister, however, he/she must be elected in the legislative assembly within six months from appointed. Therefore, Dilip Ghosh's claim is Partly True.