Dear Rithik, IELTS has no eligibility criteria. IELTS is a Language proficiency test and not an entrance examination. So it doesn't really have a eligibility criteria that Candidates need to fulfil. There are 2 types of IELTS tests, Academic and General Training. Your IELTS score for both these tests is valid for 2 years. So if you want to to go abroad after your Bachelor's degree, it makes meaning to take up IELTS in your 2nd year so that your test results do not go in vain. For test format of Academic and General Training IELTS, please visit our page at: https://www.ielts.org/en-us/about-the-test/test-format