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You can know every answer and still lose marks on the answer sheet. NEET is marked by machine from an OMR sheet, and the machine reads only what you mark. A wrong roll number, a missed bubble or a sheet torn by mistake cannot be argued afterwards. This post covers what the official bulletin says about the OMR sheet, the mistakes that cost the most, the arithmetic of marking, and a home routine that makes bubbling automatic.
The rules below come from the NEET (UG)-2026 Information Bulletin from NTA. Read the current bulletin and your admit card instructions for your own exam, and follow what the invigilator announces on the day.
How is the NEET answer sheet marked?
The bulletin describes NEET (UG) 2026 as a single-day, single-shift exam "in PEN and PAPER mode", with 180 compulsory questions to be attempted in 180 minutes: 45 in physics, 45 in chemistry and 90 in biology. Each correct answer earns +4, each incorrect one −1, and an unanswered question 0.
After the exam, NTA displays scanned images of every OMR sheet and the responses recorded by the machine, and you can challenge the machine's reading for a fee of Rs 200 per question. The bulletin also says there is no re-checking or re-evaluation of answer sheets, because "the OMRs are machine gradable". So the sheet you hand in is final.
Which OMR mistakes cost the most?
Some mistakes cost one question. Others can cost your whole result. The bulletin's list of unfair means includes:
Overwriting your roll number, test booklet number, name, parents' names or signature on the OMR sheet, or giving incorrect information there.
Erasing or obliterating any information printed on the OMR sheet.
Tearing or defacing a filled OMR sheet or any page of the test booklet.
Taking the OMR sheet (original or office copy) out of the hall.
It also says you must not leave the room "without handing over" the OMR sheet, and that results of candidates who write on another candidate's test booklet or OMR sheet will be cancelled.
The single-question mistakes are more common:
Shifted bubbles. You answer question 47 in the row for 48, and every answer after it is off by one.
Unmarked answers. You work out an answer and forget to transfer it to the sheet.
Stray or unclear marks. The machine reads what is on the sheet, not what you meant.
What does +4 and −1 mean for guessing?
The marking scheme changes the value of a guess depending on how many options you can rule out. With four options, here is the expected score from a guess, worked out:
No options ruled out: a 1 in 4 chance of +4 and a 3 in 4 chance of −1. Expected score = (1/4)(4) + (3/4)(−1) = 1 − 0.75 = 0.25.
One option ruled out: (1/3)(4) + (2/3)(−1) = 4/3 − 2/3 = 2/3, about 0.67.
Two options ruled out: (1/2)(4) + (1/2)(−1) = 2 − 0.5 = 1.5.
These are averages over many questions, not promises for one. They show why ruling out even one option makes a real difference. Our post on elimination in NEET biology MCQs shows how to do that well.
The bulletin also covers questions found to be faulty. If more than one option is correct, +4 goes to anyone who marked any correct option. If a question is dropped or no option is correct, all candidates get +4 whether or not they attempted it.
Should you change an answer?
Many students believe their first instinct is usually right. Research disagrees. In a review of this belief, Kruger, Wirtz and Miller (2005) note that most answer changes are from incorrect to correct, and that people who change answers usually improve their scores. The belief survives because a change that turns out wrong is more memorable.
On an OMR sheet, though, changing a mark is not the same as changing your mind. So settle the answer first, with a reason, and only then fill the bubble. Do not mark first and reconsider later.
How should you plan bubbling time?
With 180 questions in 180 minutes, an average of one minute per question includes bubbling. Two common plans:
Bubble as you go. Lowest risk of unmarked questions, but frequent switching between booklet and sheet.
Bubble in blocks. Finish a block of questions, say 10 or 15, then transfer them together while checking that question numbers match. Faster, but you must protect the last block.
Whichever you choose, keep a fixed point, such as the half-time signal the bulletin says will be given, to check that everything solved so far is on the sheet. A signal is also given before the close, when you must stop marking. Our guide to time management in the exam has more on pacing.
A routine to practise at home
Print a bubble sheet with 180 rows and use it for every full mock from now on.
Fill particulars first at the start of each mock, then check them aloud against a sample admit card.
Check alignment every 10 questions: the question number in your booklet should match the row on the sheet.
Score yourself with +4, −1 and 0, and log every bubbling error separately from content errors.
Do one mock with no extras. The bulletin bars pens, pencil boxes, erasers, water bottles and watches, so practise with only what the centre will allow.
When content errors outnumber bubbling errors in your log, the problem is the physics or chemistry, not the sheet. The Fermi Problem Library has worked problems with a step-by-step solver that explains the reasoning, so you can find the step where a wrong answer started.
For your next full mock, use a printed bubble sheet and count your bubbling errors before you count your score.
