IAAT is a 3-hour CBT with 60 questions (15 per subject: Physics, Chemistry, Mathematics, Biology) worth 3 marks each, totalling 180 marks with a −1 penalty for wrong answers. The exam tests aptitude for scientific research rather than rote knowledge, often presenting unfamiliar scenarios that require reasoning from first principles. The questions are typically harder than standard JEE Mains but test different skills — scientific reasoning and curiosity rather than speed in known problem types.

IISER offers a 5-year BS-MS dual degree in basic sciences across seven campuses: Pune, Kolkata, Mohali, Bhopal, Thiruvananthapuram, Tirupati, and Berhampur. Students choose their major in the third year from Physics, Chemistry, Mathematics, Biology, Earth Sciences, or Economics. The final 1.5 years involve intensive research thesis work. IISER graduates receive a research fellowship during their final-year thesis and are highly competitive for PhD admissions at IITs, TIFR, IISc, and top international universities.

Students can gain IISER admission through three channels: KVPY (SX stream) fellowship holders are directly eligible, JEE Advanced rank holders above a cutoff can apply without IAAT, and students can appear for IAAT specifically. For IAAT, students register on the IISER admissions portal, pay the application fee, and appear at designated exam centres. Admission through all three channels is merit-based, and seats are allocated through a centralized counselling process across all seven IISERs.

IISER Pune and IISER Kolkata are the most sought-after, and top ranks in IAAT or KVPY are required for admission there. IISER Mohali, Bhopal, and Thiruvananthapuram are also excellent choices with strong research infrastructure. The total intake across all 7 IISERs is approximately 1,500 students per year. Students admitted through IAAT must have scored in approximately the top 10–15% in that channel. JEE Advanced qualifiers with good ranks have a smoother admission path.

IISER BS-MS graduates are among the strongest candidates for research PhD programs globally. The five-year program with mandatory research training produces graduates with both strong theoretical foundations and hands-on research experience. A significant fraction of IISER graduates pursue PhD programs at MIT, Caltech, Harvard, Cambridge, ETH Zurich, and other top universities with full fellowships. Those who stay in India join top PhD programs at TIFR, IISc, IITs, and NCBs with a clear advantage over graduates from conventional BSc programs.