Why Subject Choice Matters
Your Leaving Cert subject choices directly affect which CAO courses you can apply for. Many courses require specific subjects at a certain level (usually Higher Level). Choosing wisely in 3rd year ensures you keep options open for 5th and 6th year.
Compulsory Subjects
Most schools require (or strongly expect) the following core subjects:
- Irish — Required unless you have an exemption (available for students who did not attend primary school in Ireland, or with specific learning difficulties)
- English — Compulsory for nearly all courses and CAO points calculation
- Mathematics — Essential for most science, engineering, business and computing courses
- A modern language — French, German, Spanish or Italian (required for many arts, languages and humanities courses)
Points Scales by Level
Higher Level subjects offer the highest potential points. Here is how they compare:
- Higher Level: H1 (90–100%) = 100 points → H7 (30–39%) = 0 points
- Ordinary Level: O1 (90–100%) = 56 points → O7 (30–39%) = 0 points
- Foundation Level: Not counted for CAO points (used for establishing a minimum entry standard)
See our Points Calculator for the full breakdown.
Strategic Subject Selection
When choosing your optional subjects (usually 3–4), consider:
- Course prerequisites: Medicine requires Chemistry (usually HL). Engineering often requires Physics and/or Maths (HL). Nursing requires a science subject.
- Bonus points for Maths: Higher Level Mathematics gives bonus CAO points — 25 extra points for H6 or above.
- Your strengths: Taking subjects you enjoy and perform well in will maximise your points total.
- Balance: A mix of essay-based (English, History, Geography) and problem-based (Maths, Physics, Accounting) subjects spreads your workload.
Popular Subject Combinations
- Medicine: Biology, Chemistry, (Physics recommended), Maths, English, Irish, a language
- Engineering: Maths (HL), Physics, Design & Communication Graphics, Applied Maths
- Law: English, History, Irish, a language, any two others
- Business: Business, Economics, Accounting, Maths, English, a language
- Computer Science: Maths (HL), Physics, Computer Science (if available)
What If Your School Does Not Offer a Subject?
Some schools cannot offer every subject. Options include:
- Enrolling in a different school nearby (if spaces allow)
- Studying the subject independently (possible for some languages)
- Taking the subject through the Post Leaving Certificate (PLC) route later
- Using an online or community-based tuition programme
Changing Subjects
Most schools allow a change of subjects within the first few weeks of 5th year. After that, it becomes more difficult — so take your time choosing and ask subject teachers for advice before finalising.