Negative marking turns every unanswered question into a decision. The rule is the same in both of these examinations, and it is worth knowing exactly what it implies before the day rather than deciding question by question under time.
The rule, as the notifications state it
- UPSC Civil Services, Preliminary Examination: for each question for which a wrong answer has been given, one-third (0.33) of the marks assigned to that question will be deducted as penalty (Examination Notice No. 05/2026-CSE, page 32). This applies to both General Studies papers.
- APPSC Group 1, Screening Test: each wrong answer will be penalised with one-third of the marks prescribed for the question (Notification No. 07/2026, page 13, para 10.2). APPSC's papers are 120 marks for 120 questions, so a wrong answer costs a third of a mark.
An unanswered question scores zero in both. The question is never "should I attempt?" in the abstract; it is "is this attempt worth more than zero, on average?"
The arithmetic
Take a question worth m marks with four options, of which one is right. A wrong answer costs m/3.
| What you know | Chance a guess is right | Expected marks from guessing |
|---|---|---|
| Nothing — a blind guess between four | 1 in 4 | ¼·m − ¾·(m/3) = 0 |
| One option ruled out — three left | 1 in 3 | ⅓·m − ⅔·(m/3) = m/9 |
| Two options ruled out — two left | 1 in 2 | ½·m − ½·(m/3) = m/3 |
| You know the answer | 1 | m |
Three things follow directly.
- A blind guess is worth nothing on average. The one-third penalty is set exactly so that random guessing between four options neither gains nor loses over many questions. It does add risk: on any one paper you may gain or lose.
- Eliminating even one option makes guessing worth it. A ninth of the question's marks is small, but it is positive, and across many such questions it adds up.
- A genuine fifty-fifty is worth a third of the marks. If you can honestly narrow a question to two options, the expected value of answering is a third of the question — not something to leave on the table.
The catch is the word honestly. Elimination only helps if the options you rule out are really wrong. An option ruled out on a hunch is not ruled out, and treating it as such quietly turns a ninth into a loss.
What it means for a qualifying paper
UPSC's General Studies Paper II (CSAT) is qualifying at 33%, and the same penalty applies to it. Here the goal is not the highest expected score but clearing the line. Two consequences:
- If you are comfortably above 33% on the questions you know, extra guessing adds risk without buying anything you need. The safe course is to stop.
- If you are short of 33% on what you know, guessing where you can eliminate options is the only way across the line, and the arithmetic above says it is worth more than nothing.
Know which of those positions you are in before the last half hour, not during it.
What it means in practice
- Practise elimination, not guessing. The skill that earns marks is ruling options out for a reason. Practice questions with explanations — like the chapter sets on PrepShark, which show why each option is right or wrong — train exactly that.
- Mark the question, not the paper. Decide per question whether you can eliminate an option, not by setting a target number of attempts in advance.
- Keep the arithmetic simple. Blind: leave it. One out: answer. Two out: answer.
The patterns themselves are explained in the UPSC Civil Services pattern and the APPSC Group 1 pattern. Check the notification for your cycle: the penalty is stated in each, and it can change.