NDA and CDS exams are national-level defence entrance exams, organised by UPSC to shortlist candidates for India’s defence academy. The National Defence Academy (NDA) and the Combined Defence Services (CDS) are joint defence training modules that directly recruit aspirants for positions in the Air Force, Navy, and Army of India.
NDA and CDS exams are some of the hardest tests held for the much sought-after defence positions in the Indian military. BYJU’s exam prep lays out the coursework, syllabus, and latest updates for easy preparation in a limited time.
Here’s all you need to know about the frequency, age limit, and eligibility of NDA and CDS exams.
Frequency to Apply for NDA and CDS
UPSC conducts NDA and CDS exams twice in a year. Hence, the candidates can apply for both the exams twice a year. However, you must ensure that you hold the required eligibility criteria that is needed to apply for the exams.
NDA: Selection Process and Exam Overview
NDA Exam is conducted by the UPSC to select personnel for the National Defence Academy. The exam is conducted to recruit candidates from the Air Force, Navy, and Army wings of the NDA.
NDA Exam: Quick Facts
- The NDA exam is only open to unmarried candidates.
- The examination is conducted in two stages: written tests and personal interviews.
- The written exam is split into two portions: The general ability test and mathematics.
- Once selected, the members are sent for a training period that lasts 3 years.
NDA Exam: Age Limit
NDA has a strict age limit for its candidates. There is a set minimum and maximum age set for application and enrollment into the training.
- The minimum age for application is 15 years old.
- The maximum age for application is 19 years old.
NDA Exam: Frequency of Application
The NDA exam is conducted twice a year, and aspirants within the age limit can give as many attempts as they can. NDA exams are usually held in the months of April and September. The registration for the exam starts 4 months prior to the main test.
CDS Exam: Basic Facts
- The CDS exam is only open to unmarried candidates.
- The exam is split into two stages: A written test and a personal interview
- Shortlisted candidates must clear an interview conducted by the Services Selection Board (SSB).
CDS Exam: Age Limit
There’s a multi-tier age limit for Air Force, Navy, and Army. Here’s how it goes:
- Indian Military Academy: Unmarried male candidates between the age of 19 to 24.
- Indian Naval Academy: Unmarried male candidates between the age of 19 to 22.
- Air Force Academy: Candidates between the age of 19 to 23.
- Officers’ Training Academy (SSC Women Non-Technical Course): Candidates between the ages of 19 to 25.
- Officers’ Training Academy (SSC Course for Men): Candidates between the age of 19 years to 25.
CDS Exam: Frequency of Application
The CDS exam is conducted twice a year, and aspirants within the age limit can give as many attempts as they can within the period of their eligibility. The biannual papers are split into CDS 1 and CDS 2. The exams are usually held in the months of April and September. The registration for the April exam (CDS 1) starts in the month of December, and the registration for the September exam (CDS 2) starts in May. The exam can be cracked with ample of focus on the major topics and following the study guide of BYJU’s exam prep.
The CDS and NDA exams are highly prestigious and competitive exams. The reason for their biannual conduction is to pool as many deserving candidates as they possibly can within their eligibility period. Aspirants who meet the physical, educational, and medical standards can apply as many times as they can, as there is no bar on the frequency of application.
NDA Exam Pattern in Brief
The NDA written exam has two papers. The first paper is Mathematics, worth 300 marks. The second paper is the General Ability Test, worth 600 marks. The General Ability Test covers English, general knowledge, physics, chemistry, general science, history, geography, and current events. The total written exam is 900 marks. Candidates who pass the written exam go to the SSB interview, which is worth 900 marks.
The SSB interview takes about five days. It includes tests of intelligence, group tasks, and a personal interview. A medical test follows. Only candidates who pass all stages join the National Defence Academy for three years of training. After NDA training, cadets go to their service academies for one more year before they become officers.
CDS Exam Pattern in Brief
| Academy | Written papers | Total marks |
|---|---|---|
| Indian Military Academy | English, General Knowledge, Elementary Mathematics | 300 |
| Indian Naval Academy | English, General Knowledge, Elementary Mathematics | 300 |
| Air Force Academy | English, General Knowledge, Elementary Mathematics | 300 |
| Officers’ Training Academy | English, General Knowledge | 200 |
Each paper lasts two hours. The SSB interview for CDS is worth 300 marks for IMA, INA, and AFA, and 200 marks for OTA. Women can apply for OTA and, since 2021, for NDA as well, after the Supreme Court opened NDA entry to women.
NDA Age Limit: The Correct Rule
The official age limit for the NDA exam is 16.5 to 19.5 years. The candidate’s age is checked on a fixed date given in the exam notice. The date differs for each exam, so always read the latest notice on the UPSC website. Unmarried male and female candidates can apply. A candidate who marries before training ends can be removed, so the rules must be read with care.
How to Apply for NDA and CDS
Step one is to read the exam notice on the UPSC website, upsc.gov.in. Step two is to fill the online form before the last date. The form asks for personal details, education, and a choice of exam centre. Step three is to pay the fee online, unless you are exempt. Women candidates and candidates from SC and ST groups are exempt from the NDA and CDS fee under current rules. Step four is to download the admit card before the exam. Step five is to take the exam at the chosen centre with a photo ID.
The exams are held twice each year. NDA I is usually held in April, and NDA II in September. CDS follows a similar pattern, with CDS I in April and CDS II in September. The exact dates change, so check the UPSC exam calendar each year.
How to Prepare for NDA and CDS
Start with the school books for maths and science. NCERT books for classes 6 to 10 cover much of the syllabus. Practice past papers under a time limit. Read a daily news source for general knowledge and current events. Work on English through reading and short writing practice.
For the SSB interview, practice group discussion and clear speaking. Stay fit, because the medical test and physical tasks matter. Join a mock SSB if you can. Start early. Six to nine months of steady study is a good plan for most candidates.
Frequently Asked Questions
How many times a year are NDA and CDS exams held?
Both exams are held twice a year by the UPSC. NDA I and CDS I are usually held in April, and NDA II and CDS II in September.
What is the age limit for the NDA exam?
The official age limit is 16.5 to 19.5 years. The exact cut-off date is given in each exam notice on the UPSC website.
Can women apply for the NDA exam?
Yes. Women can apply for the NDA exam. Entry for women opened in 2021 after a Supreme Court order.
What is the exam pattern for NDA?
The written exam has Mathematics for 300 marks and a General Ability Test for 600 marks. The SSB interview that follows is worth 900 marks.
How many attempts can I make for NDA and CDS?
There is no fixed number of attempts. You can apply as many times as you like while you meet the age and education rules of each exam.
Disclaimer: This guide is for general information only. Exam dates, age limits, fees, and rules can change. Always check the latest notice on the UPSC website before you apply.
Last Updated: 6 November 2026