The UPSC Civil Services exam for IAS is divided into three stages. These are: 1) Preliminary or prelims (which is an entry-level, objective-type test), 2) Mains examination (subjective, written exam), and the final stage is 3) Interview and Personality Test.
The preliminary exam is only meant for screening of candidates
The prelims exam stage of the IAS exam is only meant for screening purpose, implying that the test is only a gateway to appearing in the Mains exam. The marks obtained in this stage will not be added to the total score considered for rankings.
Each of the 7 papers in the non-qualifying category of the IAS mains examination make up 250 marks. These exams comprise both objective and essay type questions. Eventually, only those candidates who clear the commission-notified minimum qualifying marks will be called for Interview round.
A 275-marks final stage is conducted by the commission at the UPSC Bhawan in New Delhi.
Only those candidates who have qualified in the mains examination will be called for this round, and the board members judge them through a psychometric test, an assessment test as well as the personal interview round.