UPSC Civil Services Exam: Complete Guide to IAS, IPS, IFS & Other Services
25 Sep 2026
- Qualification
A complete overview of the UPSC Civil Services Examination — eligibility, the Prelims-Mains-Interview exam pattern, and the real structural difference between All India Services (IAS, IPS, IFoS) and Central Services (IFS, IRS, and others), including a common naming confusion worth clearing up first.
The UPSC Civil Services Examination (CSE) is India's most prestigious and competitive recruitment exam, conducted annually to fill roughly 23 different services — from IAS and IPS down to specialised Central Services most aspirants have never heard of by name. Before anything else, one naming confusion is worth clearing up: "IFS" commonly refers to the Indian Foreign Service, but there's also the Indian Forest Service (officially abbreviated IFoS to avoid this exact confusion) — and only one of these two is actually an All India Service. Getting this backwards is a common mistake.
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This guide covers eligibility, the exam pattern, and the structural difference between All India Services and Central Services. See our Civil Services Salary guide for pay across services and how the time-scale promotion system works, and our IAS, IPS and IFS guides for service-specific detail.
What Is UPSC CSE?
UPSC CSE recruits for roughly 23 services and posts in a single annual exam cycle — from the well-known IAS, IPS and IFS through numerous Group A and Group B Central Services (IRS, IDAS, IRPS, and others) most candidates only become aware of once they're deep into preparation. Selection runs through three stages: Prelims (screening only), Mains (the main written exam), and an Interview/Personality Test — with Mains and Interview marks together deciding the final merit list and service allocation.
All India Services vs Central Services: The Real Structural Difference
This distinction matters more than most guides make clear, since it affects where you'll actually work and who you report to.
| All India Services | Central Services | |
|---|---|---|
| Services | IAS, IPS, IFoS (Indian Forest Service) — only these three | IFS (Indian Foreign Service), IRS, IA&AS, IDAS, IRPS, and others (Group A and B) |
| Recruited by | Central Government | Central Government |
| Posted by | Allotted to a state cadre — officers serve the state government day to day, though they can also be deputed to the Centre | Central Government exclusively — officers serve the Union Government, not a state |
| Typical posting pattern | District/state-level administrative, police or forestry roles, with central deputation later in career | Ministries, embassies (IFS-Foreign), or specialised central departments, wherever posted nationally |
The practical takeaway: IAS, IPS and IFoS officers are recruited centrally but spend much of their career working for a specific state government (their allotted cadre), while Central Service officers (including the Foreign Service) work for the Union Government throughout, regardless of where they're posted.
UPSC CSE Eligibility
Educational Qualification: a graduation degree in any discipline — UPSC doesn't prescribe a minimum percentage, and candidates in their final year can apply provisionally.
Age Limit: generally 21 to 32 years for General/EWS candidates (as on the notification's reference date), relaxed to 35 for OBC, 37 for SC/ST, and 42 for eligible PwBD candidates.
Number of Attempts: General/EWS candidates get 6 attempts, OBC candidates get 9, and SC/ST candidates face no attempt limit (subject to the age criteria). An attempt is counted only if you appear in at least one Prelims paper — applying without appearing doesn't use up an attempt.
UPSC CSE Exam Pattern
Prelims (screening only — marks aren't carried into final merit, only used for the cutoff to Mains): two objective papers, 200 marks each (400 total), held the same day.
- General Studies Paper I: covers history, geography, polity and governance, economy, environment, science and technology, and current affairs — this paper alone determines the Prelims cutoff.
- General Studies Paper II (CSAT): comprehension, reasoning, analytical ability, basic numeracy and data interpretation — qualifying only, requiring a minimum 33%, and not used to rank candidates the way Paper I is.
Mains: nine descriptive papers totalling 1750 scored marks (Essay, four General Studies papers, and two Optional Subject papers — seven merit-counting papers in total), plus two additional qualifying-only papers (an Indian Language paper and an English paper) that must be cleared but don't add to your score.
Interview (Personality Test): worth 275 marks.
Final merit combines Mains (1750 marks) and Interview (275 marks) for a total of 2025 marks — Prelims plays no role in the final rank beyond qualifying you for Mains. See our UPSC CSE syllabus guide for the full paper-by-paper content, including GS Papers I–IV, the Essay, and the 48 optional subjects.
The Optional Subject
Mains includes an Optional Subject (two papers), and it's worth knowing this doesn't need to match your graduation degree — candidates commonly choose an optional subject unrelated to what they studied, based on scoring potential, personal interest, or overlap with the General Studies syllabus, not degree background.
Frequently Asked Questions
What is the difference between IFS and IFoS?
IFS commonly refers to the Indian Foreign Service (a Central Service, Group A), while IFoS is the Indian Forest Service, one of the three All India Services (alongside IAS and IPS). They're genuinely different services that happen to share a similar-sounding abbreviation.
How many attempts are allowed for UPSC CSE?
6 for General/EWS, 9 for OBC, and unlimited for SC/ST candidates (subject to the age limit). Only appearing in at least one Prelims paper counts as an attempt.
Does the optional subject need to match my degree?
No — the Mains optional subject can be entirely unrelated to your graduation subject; candidates choose based on scoring potential and interest, not academic background.
Is Prelims counted in the final UPSC merit?
No — Prelims is purely a screening stage to shortlist for Mains. Final merit is based entirely on Mains (1750 marks) plus the Interview (275 marks).
What is the difference between All India Services and Central Services?
All India Services (IAS, IPS, IFoS) are recruited centrally but allotted to a state cadre, meaning officers primarily serve that state government. Central Services (including IFS-Foreign, IRS, and others) are recruited and posted entirely by the Central Government, with no state cadre attachment.
Is CSAT difficult to clear?
It's qualifying only, requiring a minimum 33% — most candidates with reasonable preparation clear it, and it doesn't affect your Prelims rank the way General Studies Paper I does.
In Summary
UPSC CSE recruits for roughly 23 services through one exam, split structurally between All India Services (IAS, IPS, IFoS — state-cadre-based) and Central Services (IFS-Foreign, IRS, and others — Centre-only). Prelims is a screening gate; Mains and Interview together decide your actual rank and service allocation. Once you understand this structure, our IAS, IPS and IFS guides cover each service in full depth. See our State PSC guide for the state-level equivalent of this exam, including a genuine promotion path from State Civil Service into IAS/IPS itself, and our IAS vs IPS vs IFS comparison for how these three most-preferred services actually differ, and our UPSC vs State PSC comparison if you're deciding between the two exam routes.