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TL;DR You can retake any O-Level or A-Level subject available to private candidates, but you must retake the entire subject (all papers) -- you cannot retake individual papers. Science subjects require the practical paper too. You can then combine your best grades across sittings for L1R5, UAS, or polytechnic admission.
The short answer
As a private candidate, you can retake any subject that appears on SEAB's private candidate subject list. There is no restriction on which subjects you choose, how many you sit, or how many times you retake them.
However, there is one firm rule: you must retake the entire subject. SEAB does not allow you to retake individual papers within a subject. If you are retaking Pure Chemistry (6092), for example, you sit Paper 1 (MCQ), Paper 2 (structured/free response), and Paper 3 (practical). You cannot skip the practical and retake only the theory papers.
This applies equally to O-Level and A-Level subjects.
O-Level subjects available to private candidates
Most O-Level subjects are open to private candidates. The common ones include:
Languages
English Language (1184)
Mother Tongue Language -- Chinese (1160), Malay (1148), Tamil (1157)
Higher Mother Tongue Language -- Higher Chinese (1116), Higher Malay (1117), Higher Tamil (1147)
The full and definitive list is published by SEAB in the registration information e-booklet each year. Check the SEAB private candidates page for the latest version.
Subjects NOT available to private candidates
Some subjects require school-based coursework, internal assessment, or specialised equipment that is only available through schools:
If you previously sat one of these subjects and achieved a grade you want to keep, that grade remains valid for aggregate computation -- you simply cannot retake the subject.
A-Level subjects available to private candidates
Most H1 and H2 subjects are available to private candidates. Common ones include:
H2 subjects
H2 Mathematics (9758)
H2 Physics (9478)
H2 Chemistry (9476)
H2 Biology (9477)
H2 Economics (9570)
H2 History (9752)
H2 Literature in English (9509)
H2 Geography (9173)
H1 subjects
H1 General Paper (8881)
H1 Mathematics (8865)
H1 Economics (8843)
H1 History (8838)
H1 Geography (8834)
Subjects with restrictions
Some H2 subjects require coursework or school-based components and may not be available to private candidates. These include H2 Art, H2 Theatre Studies, and certain H2 Mother Tongue Language and Literature subjects. Always verify with the SEAB e-booklet for the current year.
H3 subjects are generally not available to private candidates as they are administered through schools.
Science subjects: you must sit the practical paper
This catches many private candidates off guard. If you are retaking a science subject -- whether O-Level or A-Level -- you must sit the practical paper as part of that retake. There is no option to skip the practical and carry forward your previous practical grade.
What this means in practice
O-Level Pure Sciences (6091, 6092, 6093): You sit Paper 1, Paper 2, and Paper 3 (practical). Paper 3 is 1 h 50 min and worth 20% of the total.
O-Level Combined Science (5086, 5087, 5088): You sit Paper 1, the relevant two theory papers for your subject combination, and Paper 5 (practical). Paper 5 is 1 h 30 min and worth 15%.
H2 Sciences (9478, 9476, 9477): You sit Papers 1--3 (theory) and Paper 4 (practical). Paper 4 is 2 h 30 min and worth 20%.
Practical training at registration
At registration, SEAB requires you to declare that you either have previously sat the same science subject, or are currently attending or will be attending a practical training course that will finish before your practical paper date.
Mother tongue, humanities, and oral/listening components
Mother tongue subjects include oral and listening components. If you are retaking a Mother Tongue subject, you sit all components -- written papers, oral examination, and listening comprehension. You cannot retake just the written paper and skip the oral.
Humanities subjects with an elective component (e.g., Social Studies with Geography) are treated as a single subject. You retake both the core and elective papers together.
Mixing old and new results
One of the most valuable rules for private candidates: you can combine your best subject grades from different sittings when applying to JCs, polytechnics, and universities.
How it works
JCs and polytechnics compute your L1R5, L1R4, or ELR2B2 using the best grade for each subject across all your O-Level sittings
For A-Level university admissions, the University Admissions Score (UAS) uses your best grade per subject across sittings
There is no penalty for having sat the exam more than once
Each sitting produces its own results slip showing only that sitting's grades, but institutions consider all sittings when computing your aggregate
Strategic implication
You do not need to retake every subject. If you scored A1 in English and Mathematics but C6 in a humanities subject, retaking just the humanities subject can improve your aggregate. Your A1 grades from the previous sitting remain valid.
Use the L1R5 calculator to model how improving specific subjects would change your aggregate.
The SEAB registration window for 2026 private candidates is 7--20 April 2026.
Step
When
Registration opens
7 April 2026
Registration closes
20 April 2026
Late registration (with $75 surcharge)
After 20 April (if available)
Written examinations
October--November 2026
Practical examinations
October--November 2026
Register through the SEAB Candidates Portal. Singapore citizens and PRs use Singpass. Foreign passport holders create an account in the portal.
Cost breakdown
Examination fees depend on citizenship status and the number of subjects.
O-Level fees (per subject, approximate)
Citizenship
Fee per subject
Singapore Citizen
~$64
Singapore PR
~$65
International candidate
~$75
A-Level fees (per subject, approximate)
Citizenship
Fee per subject
Singapore Citizen
~$75
Singapore PR
~$76
International candidate
~$90
A typical O-Level retaker sitting 3--4 subjects would pay approximately $190--$260 (Singapore citizens). Exact 2026 fees are confirmed by SEAB during the registration period.
Additional costs to budget for:
Late registration fee: $75 per examination level
Science practical training (if needed): varies by provider, typically $200--$600
Textbooks, assessment books, and past-year papers
Frequently asked questions
Can I retake just one subject? Yes. You can register for as few as one subject. Your grades from previous sittings remain valid and can be combined with new results.
Can I retake O-Levels and A-Levels in the same year? Yes. SEAB allows you to register as a private candidate for both O-Level and A-Level in the same year. The examinations are scheduled at different times within the October--November window.
What if the syllabus has changed since I last took the subject? You must follow the current syllabus. SEAB occasionally updates syllabuses and subject codes. Check the SEAB website for the latest syllabus document before registering. If content has changed significantly, you will need to study the new material.
Is there a limit on how many times I can retake? No. There is no limit on the number of times you can sit O-Levels or A-Levels as a private candidate. Each sitting produces a separate results slip.
Do universities or employers know I retook as a private candidate? The GCE certificate issued to private candidates is identical to that of school candidates. However, if you have multiple results slips from different years, institutions can see you sat the exam more than once. This is common and not viewed negatively -- what matters is your best aggregate.
