he Indian Administrative Service (abbreviated as IAS) (is the premier
Administrative civil service of the Government of India. IAS officers hold key and strategic positions in the Union Government, States the examination is conducted by the UPSC Every year .

Eligibility criteria:

Nationality:

For the Indian Administrative Service and the Indian Police Service, a candidate must be a citizen of India.
For other services, a 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 January, 1962 with the intention of permanently settling in India

Educational qualification
The candidate must hold a degree of any of Universities incorporated by an Act of the Central or State Legislature in India or other educational institutions

Age limit:
Category Maximum Age Attempt
General 32 6
OBC 32+3=35 9
SC/ST 32+5=37 As many as upto age limt
Physically
disabled 32+10=42 if general then 9
(Blind, Deaf-mute, Orthopedic) OBC then 9
SC/ST- then upto age limt

As you asking for the Application form for the IAS examination let me tell you that the Application from is not available at present you may find the Application form by going through the official site of the UPSC Notification section

for your convince here I am giving you the snapshot of that page