In short: CBSE has not published an official "how to write for OSM" rulebook that we could find. These 15 rules are practical precautions built from the failures students actually reported in 2026: blurred scans, missing pages, missing maps and graphs, and answers matched to the wrong question paper set. None of them cost extra effort. Together they make your answer book easy to scan, easy to read on a screen and easy to mark step by step.
Last updated: October 28, 2026. Figures come from the cited news reports and may change as CBSE publishes more information.
Why These Rules Exist
Under On-Screen Marking (OSM), your answer book is scanned page by page and an examiner reads the images on a computer. Press reports from 2026 described examiners zooming in repeatedly on blurred pages (Education Post). Students reported missing pages, missing maps or graphs, and an answer book evaluated against a different question set's marking scheme (The Hindu).
Some of those faults were in the system. Some can be reduced by how you write. This post is about the second kind. If you want the background first, read our OSM explainer.
Important: These are practical precautions, not official CBSE rules. Always follow your invigilator's instructions and the printed instructions on the answer book.
The 15 Rules
Before You Write
1. Fill the cover page slowly and legibly. Roll number, subject, and especially the question paper set or code. A wrong or unreadable set code is the kind of detail that can send your answers to the wrong marking scheme.
2. Check the page count before you start. Make sure your answer book is complete and not missing printed pages. Tell the invigilator immediately if it is.
3. Use one reliable pen, plus a spare of the same type. Switching between pens mid-paper means inconsistent darkness. Details in our guide on blue or black pen for OSM.
While You Write
4. Write dark and press firmly. Light strokes can fade in a scan. A pen that looks fine on paper under a bright hall light may look faint on a screen.
5. Stay inside the printed margins. Text pushed to the very edge or into the binding fold is the most likely to be cut or distorted by a scanner. Leave a visible gap on all sides.
6. Number every answer exactly as in the question paper. Write the question number in the left margin, for example "Q.17(b)". The examiner must match your answer to the right entry in the marking scheme.
7. Label every sub-part. Write (a), (b), (i), (ii) clearly. The platform asks the examiner to mark each part, so unlabelled parts are easy to overlook.
8. Leave breathing space between answers. Cramped writing is hard to read when zoomed. Skip a line between answers and between steps.
9. Show each step on its own line. In Maths, Physics and Chemistry, put each formula, substitution and result on a separate line. This makes step marking visible.
10. Do not overwrite. Strike a wrong word with a single clean line and write the correct one beside it. Overwritten letters become blobs in a scan.
11. Use a ruler for tables, underlines and straight lines. Wobbly lines add visual noise and can run into your text.
12. Box or underline the final answer. The examiner is looking for the end result and its unit. Make it easy to find.
Diagrams, Maps and Extra Sheets
13. Draw diagrams and graphs big, clean and labelled. Keep labels outside the drawing with straight leader lines. Details in our guide to diagrams and graphs under OSM.
14. Attach maps, graphs and supplementary sheets exactly as the invigilator instructs. Write your roll number on any separate sheet if told to, and note "Continued on supplementary sheet" on the main page. Missing maps or graphs were one of the complaint categories in 2026.
Rough Work
15. Keep rough work separate and clearly cancelled. Do rough work on the pages meant for it, label it "Rough work" and cross it out with a single diagonal line. Stray calculations in the middle of an answer can confuse a screen reader.
Quick Reference Table
| Problem students reported in 2026 | Rule that helps |
|---|---|
| Blurred or faint scans | 3, 4, 5 |
| Missing pages or sheets | 2, 14 |
| Missing maps or graphs | 13, 14 |
| Wrong question set evaluated | 1 |
| Missed or unmatched answers | 6, 7 |
| Missed step marks | 8, 9, 12 |
Practice any chapter on Padhaao
AI tutor for CBSE, ICSE & 15 state boards · 10 learning modes · 3 free chapters daily
Things to Avoid
| Avoid | Reason |
|---|---|
| Very light gel pens or pale ink | Fades on scan |
| Writing in the binding fold or at page edges | Can be cut or distorted |
| Heavy overwriting or scribbling | Becomes a dark blob |
| Tiny handwriting to save space | Needs constant zooming |
| Skipping the set code | Risk of mismatch with marking scheme |
| Highlighters and coloured pens | Not recommended by most schools. Check with your teacher |
Practise Before the Exam
Do your last three full mock papers in the exact style you plan to use in the hall. Then run a quick home scan test: scan one page with a phone scanning app in grayscale and view it zoomed on a laptop. If you struggle to read it, the examiner will too. For more on presentation, see our answer sheet presentation tips and handwriting guide.
Frequently Asked Questions
Are these official CBSE rules?
No. We did not find an OSM-specific writing guide from CBSE. These are practical precautions based on the problems reported in 2026. The official instructions on your admit card and answer book always take priority.
Do these rules apply if OSM is not used in 2027?
Yes. Every rule here also helps a human examiner read your paper faster. Clear numbering, visible steps and dark ink are never a disadvantage.
Does neat handwriting matter more than content?
Content earns marks, but unreadable content cannot be marked. Aim for clear, not beautiful. Our handwriting guide shows how to improve in two weeks.
Should I write on both sides of supplementary sheets?
Follow the invigilator's instructions. If both sides are allowed, make sure your ink does not show through so strongly that the other side becomes hard to read. Dark ballpoint on thin paper can show through more than you expect.
What if I realise I skipped a question number?
Write a short note at the point where the answer would have been, for example "Q.12 answered on page 9", and make sure Q.12 is clearly numbered on page 9. Do not leave the examiner to hunt for it.
Can I use a pencil for the main answers?
No. Use ink for text. For diagrams, see our diagram guide for what is generally safe.
The Bottom Line
These rules take almost no extra time once they become habit. Practise them in every mock test from now until February, so on exam day your answer book looks the same as your practice papers.
Related reading: how to write answers with subject-wise marking examples and how to avoid silly mistakes in board exams.
Related Guides
- CBSE On-Screen Marking 2027 Explained
- Blue or Black Pen for CBSE Boards — What Scans Best
- Diagrams and Graphs Under On-Screen Marking
- Step Marking in CBSE 2027 — Partial Marks
- Board Exam Answer Sheet Presentation Tips from Toppers
- How to Improve Handwriting for Board Exams
Sources
- Education Post: CBSE new re-evaluation process and blurred scans
- The Hindu: students see increase in marks after re-evaluation
₹21/mo (annual plan)
Padhaao covers 17,000+ chapters across 17 boards
Your exact syllabus. 10 learning modes. 3 free daily. Pro for unlimited - ₹21/month (annual plan).
Want the full chapter with solved examples?
10 learning modes. Board-specific content. 3 free chapters every day.
Try it free