ISRO UDC Exam Pattern 2026: Complete Guide

The ISRO UDC exam pattern sets out how the Indian Space Research Organisation tests candidates for Upper Division Clerk posts. Recruitment is run by the ISRO Centralised Recruitment Board (ICRB), and in the current cycle (Advt. No. ISRO:ICRB:01(A-JPA):2026 dated 27 July 2026) UDC candidates take the same computer-based written test as Assistants, followed by a qualifying Computer Literacy Test. UDC is a Level 4 post with a minimum basic pay of Rs. 25,500 a month.

This guide explains each stage: the four-part written paper, the marking scheme and negative marking, qualifying marks by category, the skill test and how the final merit list is prepared. It also flags what changed from the previous cycle, because many pages still show the older 120-minute paper, and gives a practical time plan for the exam.

Table of Contents

• ISRO UDC Exam Pattern at a Glance

• Key Changes to Know in the 2026 Pattern

• ISRO UDC Written Test Pattern

• Marking Scheme and Negative Marking

• Qualifying Marks for Each Category

• Skill Test: Computer Literacy Test

• Final Selection and Merit List

• What the Exam Pattern Means for You

• Time Management Strategy for the Written Test

• ISRO UDC 2026 Exam Schedule

• How to Practise in the Current Pattern

ISRO UDC Exam Pattern at a Glance

The selection process for Post No. 3 (Upper Division Clerk) has two stages. Only the written test decides your rank; the skill test is a pass-or-fail filter.

There is no interview for ISRO UDC. The official notification lists only the written test and the skill test for this post. Shortlisted candidates must, however, bring all original documents to the skill test, where the details given in the online form are checked.

Key Changes to Know in the 2026 Pattern

• Longer written test: The paper now runs for 150 minutes. The previous ICRB Assistant/UDC notification (December 2022) allowed 120 minutes for the same 200 questions, so you get 30 extra minutes.

• EWS grouped with UR for qualifying marks: The corrigendum dated 11 August 2026 clarified that UR and EWS candidates need 50% in the written test and 60% in the skill test, while OBC, SC, ST, PwBD and Ex-servicemen candidates need 40% and 50% against reserved vacancies.

• Skill test applies to UDC: Some websites state that the skill test is only for Junior Personal Assistant and Stenographer posts. The notification clearly applies the Computer Literacy Test to Posts No. 1, 3 and 5, which includes UDC.

• Revised UDC vacancies: The same corrigendum raised UDC vacancies in the Bengaluru zone from 22 to 23.

Older pages may still show a 120-minute paper or mention an interview stage, so follow the official notification and corrigenda on the ISRO website.

ISRO UDC Written Test Pattern

The written test is a single objective-type paper conducted as a Computer Based Test (CBT). It lasts 150 minutes, with compensatory time for PwBD candidates as applicable. All four parts carry equal weight.

The notification gives one overall time limit for the paper and does not mention separate timing for each part. That makes your own time plan important, which is covered later on this page.

What Each Part Tests

ISRO publishes an indicative syllabus with the notification. The table below summarises it and suggests where to begin.

Marking Scheme and Negative Marking

The written test follows a +1 and -0.25 marking pattern.

• Correct answer: You earn 1 mark.

• Wrong answer: 0.25 mark is deducted, so four wrong answers cancel one correct answer.

• Unattempted question: The notification does not prescribe any deduction for questions you leave blank.

Worked Example

Suppose you attempt 170 questions, get 145 right and 25 wrong, and leave 30 blank. Your score is 145 minus 6.25 (25 × 0.25), which equals 138.75 out of 200. Those 25 wrong answers cost you more than six correct answers, which is often the gap between being shortlisted and missing out.

When Is a Guess Worth It?

On a typical four-option question, eliminating two options leaves you a 50:50 choice. Over many such questions, each guess gains about 0.375 marks on average (half of 1 mark, minus half of 0.25). A completely blind guess gains very little on average and adds a lot of risk, so keep blind guesses to a minimum.

Qualifying Marks for Each Category

You must clear the qualifying marks in the written test to be considered for the skill test shortlist, and then pass the skill test to stay in the race.

The notification states the written test requirement as 50% or 40% marks "in Part A, B, C and D" without saying whether each part must be cleared separately. The safe plan is to score at least half the marks in every part. Remember that qualifying marks are a minimum, not a selection score; with a 1:5 shortlist, the actual score needed is usually well above it. ISRO also reserves the right to change the qualifying criteria for administrative reasons.

Skill Test: Computer Literacy Test

Based on written test performance, candidates are shortlisted for the skill test in a ratio of up to 1:5 against the category-wise vacancies, with a minimum of 10 candidates. Reserved category candidates are shortlisted separately for reserved vacancies, without counting those already shortlisted under UR. If too few candidates pass, more are called in the same 1:5 ratio to cover the shortfall.

The skill test is qualifying only, and its marks are not added to your merit. Candidates employed in Central or State Government, PSUs or autonomous bodies must bring a No Objection Certificate from their employer, or they will not be allowed to take the test. ISRO reimburses second-class train fare by the shortest route for the skill test, but no travel allowance is paid for the written test.

How to Prepare for the Skill Test

• Practise on a computer, not on paper: The syllabus is about using the software, so build documents, sheets and slides yourself.

• Cover Excel formulas well: SUM, AVERAGE, IF, sorting, filtering and simple charts appear in the official topic list and take the longest to master.

• Learn common shortcuts: Shortcut keys are named in the syllabus and save time within the 75 minutes.

Final Selection and Merit List

Final selection is based on marks scored in the written test, from among the candidates who qualify in the skill test. If two or more candidates have the same written test marks, ISRO applies these tie-breakers in order:

1. General Intelligence and Reasoning marks: The candidate with higher marks in Part C ranks higher.

2. Date of birth: If still tied, the older candidate is placed higher.

For example, if two candidates both score 138.75 and pass the skill test, the one with 41 in reasoning ranks above the one with 39. A strong reasoning score therefore helps you twice: once in the total and again in a tie.

What the Exam Pattern Means for You

• You have 45 seconds per question: 150 minutes for 200 questions works out to 45 seconds each, so speed and accuracy matter equally.

• The written test decides everything: Skill test marks do not count towards merit, so every extra mark in the CBT improves your rank directly.

• No part can be ignored: Each part carries 50 marks, and the qualifying rule is safest read as part-wise, so a very weak section is a real risk.

• The shortlist is narrow: In the 2026 cycle, UDC has 9 UR vacancies, so at a 1:5 ratio only about 45 UR candidates can be called for the skill test.

Time Management Strategy for the Written Test

The plan below is a suggested split, not an official rule. Adjust it after your first few full-length mocks based on your own strengths.

• Use the two-pass method: In the first pass, answer what you can solve quickly and mark the rest. In the second pass, return only to questions you can narrow down.

• Set a cut-off per question: If a question takes more than about 90 seconds, move on and come back later.

• Read every option: In English and reasoning, two options often look right at first glance.

ISRO UDC 2026 Exam Schedule

Tentative dates can change. Track the official ICRB recruitment page and your registered email, since call letters are sent only by email.

How to Practise in the Current Pattern

Because the pattern is fixed at 200 questions in 150 minutes, the best preparation is regular full-length practice under exam conditions. Start with topic-wise tests in each part, move to 20 to 25 minute sectional tests, and in the final weeks take full mocks and analyse every wrong or skipped answer the same day.