It depends on which institute you are trying to get admission in . For admission in central universities, CUET (Common University Entrance Test) is usually conducted, and some universities like Delhi University use this exam, so there is a definite last date for admission. Admission on the basis of 12th marks is also possible in some courses, like some central universities.

CUET (Common University Entrance Test):

For admission to Central Universities, CUET is usually conducted. Some universities like Delhi University also use CUET, as reported in Navbharat Times.

On the basis of 12th marks:

Admission in some courses is also given on the basis of 12th marks, like some central universities.

Last Date:

There is a fixed last date for admission, so you should check the admission procedure on the institute website.

Institute website:

If you want to take admission in a specific institute, you should check the admission procedure, application last date and other necessary information on their website.