Based on Nationality:
To be eligible for the India Administrative Service (IAS)and the Indian Police Service (IPS), or for other services, the candidate must be either
A citizen of India
Or a subject of Nepal
Or a subject of Bhutan
Or a Tibetan refugee who came over to India before 1st of January, 1962 and has permanently settled in India.
Or a person who is of Indian origin and has migrated from Pakistan, Sri Lanka, Burma, East African countries of Uganda, Kenya, Republic of Tanzania, Malawi, Ethiopia, Vietnam, Zambia and Zaire with the intention of permanently settling in India,
provided that a candidate belonging to (ii), (iii), (iv) and (v) must be a person in whose favour, the Government of India has issued a certificate of eligibility.

Provided further that, such candidates belonging to the category of (ii), (iii) and (iv) will not be eligible for appointment of Indian Foreign Service.
A candidate who has been appointed to the IAS and IFS via the result of an earlier examination and did continue to be a member of that service is not eligible for the examination.

Based on Age limit:
The minimum age of the candidate must be 21 years in order to be eligible and must not have attained the age of 32 years as on 1st August of the year of examination if the candidate is of general category. The upper age limit of the candidate is different based on the caste they belong to.

Category of the Candidate Number of Attempts allowed Maximum Age limit of the candidate:
General 06 32
Other backward castes (OBC) 09 35
Scheduled Caste/ Scheduled Tribe (SC/ST) Till the candidate attain age limit Till the age limit
Economically Weaker Section (EWS) 06 32
Physically disabled candidates For General and OBC candidates, 09 attempts
For SC/ST candidates, unlimited attempts till the candidate attain age limit 42

Based on qualification;
The candidate must hold a degree from any of the academic institutions/Universities which are incorporated by the Central or State Legislature in India, or any educational institutions established by an Act of Parliament or any educational institution deemed as a University under Section 3 of the University Grants Commission Act, 1956.

Candidates who have appeared for the qualifying examinations whose result has not been declared yet are eligible for the Preliminary examination. Such candidates must provide their proof of passing the said exam along with the application for the Main examination.
Candidates who hold the bachelor’s degree that is recognised by the Government are eligible to apply.
There is a minimum percentage required for graduation to be eligible for this examination.

A candidate with a professional MBBS degree or has passed any other medical degree but has not completed internship yet, is eligible provided that he/she submits a copy of the certificate from the concerned authority of the university along with the application form.

Based on physical standards;
A candidate must be physically fit according to physical standards for admission to Civil Services Examination, 2020 as per the guidelines given by Appendix – III of the Rules for Examination published in the Gazette of India extraordinary dated 12th February 2020.