How Do Extension Courses Count Towards Your ATAR?

An Extension course can contribute to your ATAR, but it does not automatically give you extra points or guarantee a higher result. What matters is how many units the course contributes, how its scaled mark compares with your other courses, and which units UAC actually selects for your ATAR calculation.

This is particularly important for Mathematics Extension 1, Mathematics Extension 2, English Extension 1, and English Extension 2. Although these courses are all called extensions, they follow different rules when UAC calculates your ATAR.

The key is to understand the difference between **studying a course, earning HSC units, and having those units included in your ATAR**. They are related, but they are not the same thing.

## The basic ATAR calculation

For NSW HSC students, UAC calculates your ATAR using an aggregate of scaled marks from 10 units of HSC courses:

- Your best 2 units of English.
- Your best 8 units from your remaining courses.

If you study more than 10 units, UAC does not simply add everything together. It selects the eligible units that produce your highest aggregate, subject to the specific rules for extension courses.

For example, a student studying 12 units might have 2 units of English and 10 other units available. Only the best 8 of those remaining units contribute to the ATAR.

[IMAGE: An educational illustration of the NSW ATAR's 10-unit calculation. Show a clearly separated 2-unit English section and 8-unit remaining-courses section, with additional eligible units sitting outside the final calculation. Label the diagram to show that UAC selects the best eligible units rather than automatically counting every course.]

One important detail: UAC uses scaled marks, not simply your original HSC examination marks. Scaling changes the marks used in the aggregate so that students studying different course combinations can be compared. It does not award a fixed bonus for choosing a particular subject.

For a fuller explanation, see [How Does HSC Scaling Work? From HSC Marks to ATAR](https://tutorgum.com/learn/resources/how-does-hsc-scaling-work/).

The rules below are based on UAC's published NSW ATAR information for the **2026 HSC cohort**, applying for university entry in 2027, as at 8 November 2026.

01How English Extension 1 and Extension 2 count

English extensions work differently from mathematics extensions.

The HSC unit values are:

You can earn four HSC units across these courses, but UAC only needs your best two English units for your ATAR.

The important rule is that UAC uses the highest scaled marks available from your English courses to fill those two units. It doesn’t automatically count English Advanced just because it’s your main English course.

There is also a sequence requirement:

• You must satisfactorily complete English Advanced for English Extension 1 to contribute.
• You must satisfactorily complete English Extension 1 for English Extension 2 to contribute.

You can complete the courses in different years, provided you meet the relevant NESA requirements.

02How Mathematics Extension 1 and Extension 2 count

Mathematics is more complicated because Extension 1 changes its ATAR unit weighting when you complete Extension 2.

Start with the course values:

If you complete Mathematics Advanced and Extension 1, you have three units of calculus-based mathematics available for your ATAR.

However, if you satisfactorily complete all three courses, UAC changes how those units contribute.

The calculation becomes:

• Mathematics Advanced: 0 units included.
• Mathematics Extension 1: 2 units included.
• Mathematics Extension 2: 2 units included.

That’s four units of mathematics in your ATAR, not five.

Why does Extension 1 double?

UAC doubles the mark from Mathematics Extension 1 when it is paired with Mathematics Extension 2. This gives Extension 1 a two-unit weighting in the ATAR calculation.

The result is that your Mathematics Advanced mark is left out of the aggregate, even if it was your strongest mathematics result.

03Do you need an Extension course to qualify for an ATAR?

No. You do not need to study Mathematics Extension 1, Mathematics Extension 2, English Extension 1, or English Extension 2 to receive an ATAR.

You do, however, need to satisfy UAC’s eligibility requirements. For NSW students, these include:

• At least 10 units of HSC Board Developed courses.
• At least 2 units of English.
• At least three Board Developed courses worth 2 units or more.
• Courses from at least four subject areas.

The four-subject-area requirement catches students out.

Courses and subject areas are not the same thing

Imagine a student takes:

• English Advanced
• English Extension 1
• English Extension 2
• Mathematics Advanced
• Mathematics Extension 1
• Mathematics Extension 2
• Biology

That’s seven courses, and the student has more than 10 HSC units.

But there are only three subject areas:

1. English
2. Mathematics
3. Biology

The English extensions belong to the English subject area. The mathematics extensions belong to the Mathematics subject area. They don’t create additional subject areas.

The student therefore does not meet UAC’s four-subject-area requirement.

Adding Chemistry, for example, would provide a fourth subject area, assuming the other eligibility requirements are also met.

This is why having lots of courses or units does not automatically make you ATAR-eligible.

You can check the complete requirements in UAC’s ATAR eligibility guide.

NESA’s HSC rules are a separate requirement

There are two sets of rules worth keeping separate:

For example, NESA requires students to complete the relevant preceding courses to maintain eligibility for an extension course.

Under its current rules:

• HSC English Extension 1 requires the relevant Preliminary English courses and concurrent or prior completion of HSC English Advanced.
• HSC English Extension 2 requires HSC English Advanced and English Extension 1.
• HSC Mathematics Extension 1 requires the relevant Preliminary Mathematics courses and concurrent or prior completion of HSC Mathematics Advanced.
• HSC Mathematics Extension 2 requires the relevant Preliminary Mathematics courses and concurrent or prior completion of HSC Mathematics Extension 1.

These requirements are not the same as UAC’s rules for calculating the ATAR.

You can read the detailed requirements in NESA’s ACE Rules for extension-course eligibility.

There is also a separate NESA pattern of study for receiving the HSC. For example, students must complete at least 12 Preliminary units and 10 HSC units, with the required English, subject, and course coverage.

Meeting the HSC requirements does not automatically mean you meet UAC’s ATAR eligibility requirements.

04Do universities require you to study Extension courses?

Sometimes, but there is no universal university requirement that every student must study an Extension course.

This is where you need to distinguish between four things:

• NESA requirements: The formal rules governing which HSC courses you can undertake.
• UAC requirements: The rules governing your ATAR calculation and eligibility.
• University prerequisites: Specific academic requirements for admission to a particular degree.
• School requirements: Your school’s own subject-selection policies, course availability, and timetable arrangements.

A university prerequisite applies to the relevant university course. It does not automatically become a statewide requirement for NSW students.

Consider two examples for university entry in 2027.

Example 1: The University of Sydney

The University of Sydney has mathematics prerequisites for selected degrees, including Engineering and Advanced Computing.

For NSW HSC applicants, its published requirement is:

• Mathematics Advanced: Band 4, or
• Mathematics Extension 1 or 2: Band E3.

This means a student can satisfy the mathematics prerequisite through Mathematics Advanced without necessarily needing an Extension result.

The requirement applies to the specified University of Sydney courses, not every university degree in NSW.

See the University of Sydney’s mathematics prerequisite requirements.

Example 2: Australian National University (ANU)

ANU’s 2027 Bachelor of Engineering (Honours) lists NSW HSC Mathematics Advanced or equivalent as its mathematics prerequisite.

It does not list Mathematics Extension 1 as a compulsory prerequisite for that degree.

See the ANU Bachelor of Engineering (Honours), 2027 course information.

These examples show why you should check the actual degree you want to study rather than assuming that every engineering, science, or mathematics degree has the same requirements.

Also, don’t confuse a prerequisite with assumed knowledge. A university might expect you to have studied a particular subject because it provides useful preparation, without making it a formal condition of admission.

05Does your school decide whether you can study Extension?

Your school has a role in subject selection, but it cannot change UAC’s ATAR calculation rules.

Schools decide which courses they offer and how they organise their timetable. They may also have local selection policies, such as recommending particular Year 11 results before allowing a student into an Extension class.

These are school-level decisions, not automatic statewide ATAR requirements.

For example, if your school recommends a strong result in Mathematics Advanced before selecting Mathematics Extension 1, that is different from saying NESA requires a particular HSC mark for Extension 1.

When you’re unsure, ask your school whether a restriction comes from:

• A formal NESA course-eligibility rule.
• A university prerequisite for a particular degree.
• Your school’s own subject-selection policy.

That distinction can make a real difference when you’re deciding which courses to study.

06Should you study an Extension course?

Understanding the unit calculations is only half the decision. You also need to consider whether the course suits your strengths and future plans.

An Extension course can be valuable even if it doesn’t contribute all its units to your ATAR. It may develop skills and knowledge that prepare you for university.

For example:

• Mathematics Extension 1 develops deeper mathematical reasoning and prepares you for more advanced mathematical study.
• Mathematics Extension 2 provides further mathematical depth, which can be useful for calculus-heavy university degrees.
• English Extension 1 develops more advanced literary analysis and independent interpretation.
• English Extension 2 involves producing an independent Major Work, requiring sustained planning, composition, and reflection.

But these benefits come with additional work.

Consider three factors before selecting an Extension course.

1. Your existing ability

Do you understand the underlying course material well enough to tackle more difficult problems?

For Mathematics Extension, a strong foundation in Mathematics Advanced is particularly important. If you’re already struggling with algebra, functions, or calculus, adding another layer of difficulty may not be the best move yet.

2. Your interest in the subject

Extension courses involve more than just learning extra content. They require you to spend time thinking about challenging problems and ideas.

If you genuinely enjoy mathematics, literature, or independent research, that interest can help you sustain the workload.

3. Your future university plans

Check whether your intended degree has a formal prerequisite, recommended study, or assumed knowledge.

An Extension course may provide useful preparation without being compulsory for admission.

And remember: choosing a course because it traditionally scales well is not a reliable strategy on its own.

UAC recalculates scaling each year using the performance of students across their courses. Mathematics Extension 2 has traditionally scaled strongly, but that does not mean every student will receive a higher scaled mark or ATAR by taking it.

Your own performance matters.

For a closer explanation of why, read How Does HSC Scaling Work? From HSC Marks to ATAR.

07Can you complete Extension courses in different years?

Yes. You don’t necessarily need to complete the main course and its Extension course in the same year.

UAC allows students to accumulate HSC courses towards their ATAR over a rolling period of up to five years, subject to school approval and the relevant NESA requirements.

For example, you might complete English Advanced in one year and English Extension 1 in a later year.

There are two important conditions:

1. You must satisfy the relevant NESA course eligibility and completion requirements.
2. The corresponding course must be satisfactorily completed before the extension result can contribute to your ATAR.

Your scaled marks are calculated in the year you complete each course, not retrospectively in the year you receive your ATAR.

See UAC’s rules for accumulated and accelerated courses.

An important clarification about Mathematics: UAC’s published ATAR guidance states that Mathematics Extension 1 and Extension 2 can be completed without completing Mathematics Advanced. However, NESA’s current published ACE eligibility rules require HSC Mathematics Advanced for HSC Mathematics Extension 1. These official pages are not aligned in their wording. Do not interpret UAC’s ATAR calculation guidance as permission to enrol in a course pattern that NESA does not allow. If your school proposes a non-standard pathway, ask it to confirm your eligibility with NESA before enrolling.

08Questions and solutions

Question 1

A student satisfactorily completes English Advanced, English Extension 1, and English Extension 2.

Their illustrative one-unit scaled marks are:

Which two English units contribute to the student’s ATAR aggregate? Calculate their combined contribution.

Solution 1

English Extension 1 and English Extension 2 contribute, giving a combined scaled contribution of 78.

The student has four eligible English units available, but UAC only requires the best two.

The three possible course results, expressed on a one-unit basis, are 36, 40, and 38. The two highest are:

\[ 40+38=78 \]

English Advanced is excluded from this particular aggregate calculation because both extension results are higher.

The important point is that English Advanced does not automatically take priority simply because it is the two-unit course. UAC selects the best eligible English units.

Question 2

A student satisfactorily completes Mathematics Advanced, Mathematics Extension 1, and Mathematics Extension 2.

Their illustrative one-unit scaled marks are:

Calculate:

a) The number of mathematics units included in the ATAR aggregate.

b) The combined scaled contribution from mathematics.

Explain why Mathematics Advanced is or isn’t included.

Solution 2

Four mathematics units contribute to the ATAR aggregate, with a combined illustrative scaled contribution of 160.

Step 1: Apply the Extension 1 weighting.

Because the student has satisfactorily completed Extension 2, the Extension 1 mark is doubled.

\[ 39\times 2=78 \]

Extension 1 therefore contributes two units.

Step 2: Calculate the Extension 2 contribution.

Extension 2 is already a two-unit course.

\[ 41\times 2=82 \]

Step 3: Exclude Mathematics Advanced.

When all three courses are satisfactorily completed, UAC uses the Extension 1 and Extension 2 results and ignores Mathematics Advanced in the aggregate.

Even though Mathematics Advanced has the highest one-unit scaled mark of 43, it does not contribute.

Step 4: Calculate the total.

\[ 78+82=160 \]

The mathematics contribution is four units, not five.

This is the key difference between the number of HSC units a student completes and the number of units UAC actually uses.

Question 3

A student satisfactorily completes the following HSC courses:

The student believes they qualify for an ATAR because they have completed 11 units across seven courses.

Are they correct? Explain the eligibility problem and suggest one change that would resolve it.

Solution 3

No. The student does not satisfy the four-subject-area requirement for ATAR eligibility.

Although the student has 11 units and seven course entries, their studies cover only three subject areas:

1. English
2. Mathematics
3. Biology

English Extension 1 and Extension 2 do not count as additional subject areas. The same applies to Mathematics Extension 1 and Extension 2.

The student therefore needs another subject area.

For example, adding Chemistry would give them four subject areas:

• English
• Mathematics
• Biology
• Chemistry

Assuming all other UAC eligibility requirements are satisfied, this would resolve the subject-area problem.

The tempting mistake is to count course names instead of subject areas. UAC treats these as different things.

Question 4

A student wants to study Mathematics Extension 1.

Their school tells them that NESA requires every student to achieve at least a Band 5 in Mathematics Advanced before they can enrol.

The student checks the NESA ACE Rules and cannot find this specific mark requirement.

Is the school’s statement an accurate description of a statewide NESA requirement? Explain the difference between NESA’s course eligibility rules, school selection policies, and UAC’s ATAR rules.

Solution 4

No. NESA’s published course eligibility rules do not specify a universal Band 5 requirement for Mathematics Extension 1.

NESA requires students undertaking HSC Mathematics Extension 1 to have satisfactorily completed the relevant Preliminary Mathematics Advanced and Mathematics Extension 1 courses, and to complete HSC Mathematics Advanced concurrently with or before Extension 1.

A school may impose its own additional selection threshold or recommend a particular level of achievement before allowing students into an Extension class.

That is a local school policy, not a statewide NESA Band 5 requirement.

UAC’s role is different again. It determines how eligible mathematics results contribute to the ATAR aggregate. It does not require students to study Mathematics Extension 1 to receive an ATAR.

The correct approach is to ask the school whether its Band 5 threshold is a formal local enrolment condition, a recommendation, or a timetable-related decision.

Question 5

A student has completed the following courses satisfactorily and is preparing applications for university entry in 2027.

Their illustrative scaled marks are given on a one-unit basis. These are invented values for this question, not actual HSC scaling figures.

The student has also achieved a Band 4 in Mathematics Advanced.

They are considering:

• A University of Sydney Engineering degree that appears on its mathematics prerequisite list.
• ANU’s 2027 Bachelor of Engineering (Honours).

Answer all four parts:

a) Identify the exact 10 units that contribute to the student’s ATAR aggregate.

b) Calculate the illustrative scaled aggregate from those units.

c) Mathematics Advanced is excluded from the ATAR calculation. Can the student still use their Mathematics Advanced HSC result to satisfy the mathematics prerequisites of the two university courses?

d) Does the student’s overall course combination satisfy UAC’s four-subject-area requirement?

Solution 5

The student has an illustrative 10-unit aggregate of 406, and their Band 4 Mathematics Advanced result can still satisfy the mathematics prerequisite for both of the specified university courses. Their combination also satisfies the four-subject-area requirement.

This question tests several rules at once. The key is to separate ATAR aggregation from HSC results and university admission requirements.

Step 1: Select the two English units.

The student has four English units available.

Their one-unit scaled marks are:

• English Advanced: 38
• English Extension 1: 42
• English Extension 2: 36

The two highest are English Extension 1 and English Advanced.

\[ 42+38=80 \]

English Extension 2 is excluded.

Step 2: Calculate the mathematics contribution.

The student has satisfactorily completed all three mathematics courses.

Therefore, Mathematics Advanced is excluded, Mathematics Extension 1 is doubled, and Mathematics Extension 2 contributes two units.

The calculation is:

\[ (41\times 2)+(40\times 2) \]

\[ =82+80=162 \]

Four mathematics units contribute to the aggregate.

Step 3: Select the remaining four units.

The student has eight units available across Physics, Chemistry, and Modern History.

Their scaled marks per unit are:

The highest four units come from Physics and Modern History.

\[ (43\times 2)+(39\times 2) \]

\[ =86+78=164 \]

Chemistry is excluded from the aggregate.

Step 4: Confirm the 10-unit selection.

The final selection is:

The aggregate is:

\[ 80+162+164=\boxed{406} \]

This is an illustrative scaled aggregate, not an ATAR score. UAC converts the aggregate into an ATAR rank using the relevant year’s distribution.

Step 5: Check the university prerequisites.

The student can still use their Mathematics Advanced result.

The fact that UAC excludes Mathematics Advanced from the ATAR aggregate does not erase the HSC result or prevent a university from considering it as evidence of prerequisite knowledge.

For the University of Sydney courses covered by its mathematics prerequisite policy, a Band 4 in Mathematics Advanced satisfies the stated NSW HSC mathematics requirement.

For ANU’s 2027 Bachelor of Engineering (Honours), the published NSW prerequisite is Mathematics Advanced or equivalent. The student has completed Mathematics Advanced.

Therefore, the student meets the mathematics prerequisite for both examples, subject to the other applicable admission requirements.

This does not guarantee an offer. The student must still satisfy the relevant selection rank and other course requirements.

Step 6: Check the subject areas.

The student’s courses cover five subject areas:

1. English
2. Mathematics
3. Physics
4. Chemistry
5. Modern History

They therefore satisfy the four-subject-area requirement.

The important conceptual distinction is that a course can be excluded from your ATAR aggregate while its HSC result remains useful for university admission.

A subject’s contribution to your ATAR and its usefulness for entering a university degree are two separate questions.

09What should you remember when choosing Extension courses?

There are three different questions to ask before choosing an Extension course:

1. Will I be eligible to study it? Check NESA’s course requirements and your school’s selection policy.
2. How will it contribute to my ATAR? Check UAC’s unit-weighting and scaled-mark rules.
3. Will it help me prepare for or enter my intended degree? Check the university’s actual prerequisites and assumed knowledge for your intended intake.

Don’t choose an Extension course simply because you expect it to scale well. A course’s scaling is not a fixed bonus, and completing more units does not guarantee a higher ATAR.

Instead, consider your ability, interest, workload, and future study plans alongside the actual calculation rules.

If you’re still working out how your complete HSC subject combination fits into the 10-unit calculation, read Which Units Count Towards Your ATAR? NSW HSC Rules Explained.

Understanding that calculation is the starting point for making a sensible subject-selection decision.