IFoS Optional Subjects List 2026 For Mains

Indian Forest Service (IFoS) Examination 2026 is designed to recruit officers for managing India’s forests, wildlife, and natural resources. One of the most important parts of the IFoS Main Examination is the selection of optional subjects. IFoS Optional Subjects allow candidates to choose two specialized disciplines in which they have strong academic interest and knowledge. These subjects carry a large weightage in final merit and can greatly influence rank and selection.

IFoS Optional Subjects

IFoS Optional Subjects are specialized topics for the Indian Forest Service Main Examination. They allow candidates to showcase deep conceptual understanding, analytical ability, and subject expertise. Since the IFoS exam focuses on scientific and technical knowledge, most optional subjects are drawn from core science and engineering backgrounds.

IFoS Optional Subjects List

The Indian Forest Service Examination requires every Mains-qualified aspirant to select two optional subjects from a list provided officially by UPSC. Each optional subject has:

• Two written papers
• 200 marks per paper
• Total 400 marks for optional section

Thus, optional subjects are the backbone of the IFoS Mains stage.

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Subject Choices

Candidates select two subjects from the following comprehensive IFoS Optional Subjects list:

• Agriculture
• Agricultural Engineering
• Animal Husbandry & Veterinary Science
• Botany
• Chemistry
• Chemical Engineering
• Civil Engineering
• Forestry
• Geology
• Mathematics
• Mechanical Engineering
• Physics
• Statistics
• Zoology

Specific rules apply to subject combinations. These prevent candidates from selecting overlapping or too many related fields.

IFoS Mains Subject Combination Rules

The IFoS Mains examination does not allow free combination of any subjects. UPSC has framed strict rules so that candidates select balanced and non-overlapping fields.

Disallowed Combinations

Candidates cannot combine certain subjects. These restrictions include:

• Agriculture with Agricultural Engineering
• Agriculture with Animal Husbandry & Veterinary Science
• Agriculture with Forestry
• Chemistry with Chemical Engineering
• Mathematics with Statistics

Engineering Subject Limitation

Another important rule is:

• A candidate can select only ONE engineering subject from the group:
  • Agricultural Engineering
  • Chemical Engineering
  • Civil Engineering
  • Mechanical Engineering

So an aspirant cannot choose Civil Engineering + Mechanical Engineering together. This keeps the assessment diversified.

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Syllabus Standard

Optional subject papers generally follow an Honours Degree level syllabus. This standard is above a Bachelor’s but below a Master’s degree. However, engineering subjects are set at the Bachelor’s Degree level. There are no practical examinations. All written papers are conventional essay type and must be answered in English.

Rules of Indian Forest Service Exam Optional Subjects

Understanding the specific rules for Indian Forest Service Exam optional subjects is important. This covers the exam structure and subject choice limitations.

Examination Pattern

The IFoS exam starts with the Civil Services (Preliminary) Examination. This is a screening test with two objective papers. Prelims marks do not count for final merit. Successful candidates then appear for the Main Examination.

The Main Examination comprises a written test and an interview. The written test has six papers. Two papers are from the candidate’s chosen optional subjects. The interview is a Personality Test.

Subject Combination Rules

Strict rules govern subject selection. As noted earlier, certain subject pairings are prohibited. This ensures fairness. Also, candidates may only choose one subject from the engineering disciplines. These rules define the framework for optional subject choices.

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Scoring and Selection

The final ranking relies on marks from the Main Examination. This includes both the written test and the interview. The interview component carries 300 marks. No minimum qualifying marks apply to the interview. Strong performance in Indian Forest Service Exam optional subjects is essential for a high score.

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