The CDS exam pattern explained

The Combined Defence Services (CDS) examination is UPSC's route for graduates into the officer academies of the Army, Navy and Air Force. It is held twice a year, and every cycle follows the same basic design: a one-day written exam that filters candidates, then a five-day Services Selection Board (SSB) that tests something quite different, and a final merit list that adds the two together.

Most candidates know the three paper names. Fewer have thought about what the structure demands: one minute per question in two papers, a penalty for every careless answer, and an interview stage worth as much as the entire written exam. This guide walks through each piece and what it means for how you prepare.

Two cycles a year

UPSC runs CDS (I) and CDS (II) each year. In recent years the pattern has been roughly this:

Dates move, so treat the table as a rhythm, not a calendar. What matters is that a missed cycle is only six months away, and an eligible candidate can take several attempts before crossing the age limit. There is no cap on attempts in CDS; only the age window limits you.

Which papers you take

If you apply for OTA only, you do not sit the maths paper at all. If you apply for OTA and any of the other three, you sit all three papers; your OTA score is simply calculated on English and GK.

The three papers

• All three are objective, multiple-choice papers with four options, answered on an OMR sheet.
• Negative marking: one-third of the marks for that question is deducted for each wrong answer. Marking more than one option counts as a wrong answer. A blank costs nothing.
• The English paper is set in English only. GK and Maths are bilingual (Hindi and English).
• The papers usually run on the same day, one after another, with breaks in between. Check your admit card for the exact session timings.

What the timing means

English and GK give you 120 questions in 120 minutes: one minute each, with no spare time for rereading a long comprehension passage twice. Maths gives you 100 questions in 120 minutes, or 72 seconds each. That sounds generous until you meet a geometry question that needs a diagram and three steps.

So the written exam is as much a speed test as a knowledge test. You will see this again and again: a candidate who knows the material but has never practised full papers under a clock often leaves 15 to 20 questions untouched.

The SSB

Candidates who clear the written cut-off for an academy are called to the Services Selection Board (SSB). It runs over about five days in two stages:

1. Stage I (screening): an intelligence test and a picture perception and discussion test. Candidates not screened in return home the same day.
2. Stage II: psychological tests, group testing officer (GTO) tasks and a personal interview, spread over the next few days.
3. Conference: on the last day, the board assessors meet each candidate briefly and decide on recommendations.

AFA candidates also take the Computerised Pilot Selection System (CPSS). Recommended candidates then face a detailed medical examination; medical fitness is a condition of the final merit list. For the full SSB routine, see the SSB overview.

Final merit

The final merit list adds written and SSB marks:

A worked example shows why the SSB matters so much. Suppose two hypothetical candidates apply for IMA:

Candidate A beat B by 30 marks in the written exam and still finished 20 marks behind. The written exam gets you into the SSB room; after that, both halves count equally.

How the stages work together

The written exam is a filter: it decides who is called to the SSB. Because each academy has a limited number of vacancies, cut-offs can be high, and every question matters, which is why accuracy under negative marking deserves serious practice. You can read more in the guide to negative marking in CDS.

At the SSB, the assessment changes completely. There are no right answers to memorise. Assessors watch how you think, speak, cooperate and handle situations over several days. A candidate who has prepared only for the written papers often finds the SSB unfamiliar, and the gap between the written result and the SSB date is short, often a few months. Prepare for both from the beginning.

What the pattern tells you

Common mistakes

• Treating the written exam as the finish line. The SSB is half your final score.
• Ignoring the clock. Knowing the answers is not enough if you reach only 95 of 120 questions.
• Leaving maths to the end. It is the paper where practice hours pay back most reliably, and the one many humanities graduates fear most.
• Guessing blindly to "attempt everything". With a one-third penalty, blind guesses gain nothing on average.

Quick self-check

1. How many marks does the written exam carry for OTA? 200 (English and GK only).
2. How much is deducted for a wrong answer in the maths paper? One-third of a mark.
3. What is the final merit total for IMA? 600: 300 written plus 300 SSB.
4. How long do you have per question in the GK paper? About one minute.
5. Is a blank answer penalised? No. Only wrong answers, including multiple marked options, attract the penalty.

Next, read the CDS syllabus, analysed to see what each paper covers, then take one recent previous-year paper under timed conditions. Your score on that first paper will tell you more about where to start than any plan.