Census 2027 — Key Facts for UPSC

Census 2027 Key Dates and Timeline (UPSC Quick Reference)

Master timeline of Census 2027 (all dates confirmed from official sources unless marked):

• 30 April 2025: Cabinet Committee on Political Affairs (CCPA) decides to include caste enumeration in Census 2027 (PIB, confidence: high).
• 16 June 2025: Intent to conduct Population Census 2027 notified in the Gazette of India under the Census Act, 1948; census process formally commences (PIB/ORGI gazette, confidence: high).
• 11 March 2022 (background): Census (Amendment) Rules 2022 notified, permitting census schedules in electronic form and self-enumeration — the legal enabler of the digital census.
• 12 December 2025: Union Cabinet approves financial outlay of Rs 11,718.24 crore for Census 2027 (newsonair/PIB, confidence: high).
• 1 January 2026: Administrative boundaries/units FROZEN as of this date to provide a stable frame (PIB Backgrounder, confidence: high).
• November 2025: Nationwide pre-test for Phase I covering ~5,000 census blocks (PIB Backgrounder, confidence: high).
• January 2026 (reported 22-23 January): Government notifies the 33 questions for Phase I Houselisting and Housing Census (newsonair, confidence: high).
• 5 March 2026: HM Amit Shah soft-launches four digital census tools and unveils official mascots 'Pragati' and 'Vikas' (newsonair/DD News, confidence: high).
• 1 April - 30 September 2026: Phase I — Houselisting and Housing Census (HLO); each State/UT picks a 30-day window, preceded by an optional 15-day self-enumeration window. Field operations commenced in six States/UTs on 1 April 2026 (newsonair, confidence: high).
• 17-31 August 2026: Self-enumeration window for Population Enumeration in UT of Ladakh and snow-bound areas of J&K, Himachal Pradesh, Uttarakhand (Daily Excelsior/ANI, confidence: high).
• 14 August 2026: RGI notifies the 40-question Household Schedule for Phase II Population Enumeration (Civilsdaily/Deccan Herald, confidence: high).
• 1-30 September 2026: Phase II Population Enumeration in Ladakh and snow-bound areas; reference date 00:00 hrs of 1 October 2026. Ladakh set to be the first UT to complete Census 2027 (ladakh.gov.in/Daily Excelsior, confidence: high).
• February 2027: Phase II Population Enumeration for the rest of India (official). Wikipedia lists 9-28 February 2027; exact all-India dates per final notification — treat the precise window as unconfirmed. (Note: 9-28 February was the 2011 PE window, a possible source of conflation.)
• 00:00 hrs, 1 March 2027: Reference date ('Census Moment') for most of India (gazette notification, confidence: high).
• Late 2027 / late 2028: Provisional and final results expected (Wikipedia, confidence: unconfirmed).

Census 2027 Key Numbers Every Aspirant Must Memorize

Numbers most likely to be tested in prelims (all from PIB Backgrounder 'Census 2027: India's First Digital Enumeration Exercise', 25 April 2026, unless noted):

• Budget/outlay: Rs 11,718.24 crore approved by Union Cabinet (12 December 2025). Early media estimates had said ~Rs 13,000 crore (Deccan Herald, June 2025) — the approved figure is 11,718.24.
• Serial number: 16th Census of India overall; 8th since Independence.
• Workforce: approximately 31 lakh enumerators and supervisors, plus over 1 lakh census functionaries (PIB). Some reports round this to 30-34 lakh; Wikipedia says 3.3 million. Use '~31 lakh + 1 lakh functionaries' as the official figure.
• Training: more than 80,000 training batches per phase.
• Technical manpower: ~18,600 engaged for ~550 days at local levels; ~1.02 crore man-days of employment generated.
• Phase I questions: 33 notified questions (housing conditions, amenities, assets); the official PIB graphic lists 34 items — item 34 is the mobile number, collected only for census-related communication.
• Phase II questions: 40 questions (up from 29 in Census 2011); 13 questions are new.
• Languages: mobile app and Self-Enumeration Portal in 16 languages (Assamese, Bengali, English, Gujarati, Hindi, Kannada, Konkani, Malayalam, Manipuri, Marathi, Nepali, Odia, Punjabi, Tamil, Telugu, Urdu); instruction manuals prepared in 19 languages.
• Administrative units (2011 vs 2027): States/UTs 35 vs 36; Districts 640 vs 784; Sub-districts 5,990 vs 7,092; Statutory towns 4,041 vs 5,128; Census towns 3,892 vs 4,580; Villages 6,40,932 vs 6,39,902 (note: villages DECREASED — a classic trap question).
• Pre-test: ~5,000 census blocks, November 2025.
• Data security: end-to-end encryption; data centres designated Critical Information Infrastructure (CII); ISO/IEC 27001:2022 compliant.
• Self-enumeration uptake: over 5.72 lakh households by 10 April 2026; ~82 lakh households by mid-August 2026 (newsonair/ANI).

The 'Firsts' of Census 2027

Census 2027 'firsts' — high-probability prelims fodder:

1. FIRST DIGITAL CENSUS of India: data collected via mobile app (Android and iOS) by enumerators, transmitted field-to-server with no paper schedules; billed as the world's largest census exercise and India's first fully digital one (PIB).
2. FIRST SELF-ENUMERATION option: households can fill their own schedules online via the Self-Enumeration Portal (se.census.gov.in) during a 15-day window before house-to-house visits; a unique Self-Enumeration ID (SE ID) is generated and later confirmed by the enumerator.
3. FIRST CASTE ENUMERATION since 1931: all castes to be enumerated (not just SC/ST as in every census from 1951 to 2011). Decision taken by the Cabinet Committee on Political Affairs on 30 April 2025. Caste is asked in Phase II (Population Enumeration); caste appears as question 10 of the 40-question household schedule alongside the SC/ST query (Deccan Herald/Millennium Post). Note: 1941 census collected caste but data was not tabulated/published due to WWII (standard historical account, widely reported — confidence: medium); SECC 2011 collected caste but its caste data was never fully released.
4. FIRST near-real-time monitoring: Census Management and Monitoring System (CMMS) portal — officers at sub-district, district, state and national levels track progress on dashboards.
5. FIRST use of satellite-imagery-based digital block creation: Houselisting Block Creator (HLBC) web mapping application used by Charge Officers, with geo-referenced jurisdictions to avoid omission/duplication.
6. FIRST census with 36 States/UTs (2011 had 35) — includes UT of Ladakh and merged UT of DNH & Daman-Diu created after 2019.
7. FIRST census after a 16-year gap: Census 2021 could not be held due to COVID-19 — the first break in the unbroken decennial series since 1881.
8. FIRST census where data centres are designated Critical Information Infrastructure (CII).
9. Ladakh: first UT to complete the entire Census 2027 exercise (PE 1-30 September 2026).

Constitutional and Legal Basis of the Census

Legal-constitutional framework (frequently asked in prelims):

• CONSTITUTION: 'Census' is a Union subject — Entry 69 of the Union List (List I), Seventh Schedule, read with Article 246. The Constitution does NOT mandate a decennial census; the 10-year cycle is a practice, not a constitutional requirement (Drishti IAS).
• CENSUS ACT, 1948: the governing statute, piloted by Sardar Vallabhbhai Patel as Home Minister (Drishti IAS). Provides for census officers' appointment, citizens' obligation to answer, and penalties. Enacted BEFORE the Constitution came into force.
• SECTION 15, Census Act 1948: individual census records are strictly confidential — 'not open to inspection nor admissible in evidence' in any court; also exempt from disclosure under the RTI Act; cannot be shared with any institution (PIB Backgrounder). Classic prelims point: census data cannot be used as evidence in court.
• CENSUS RULES, 1990: operational rules framed under the Act.
• CENSUS (AMENDMENT) RULES, 2022: notified 11 March 2022; allowed census schedules 'in paper or electronic form' and introduced self-enumeration (defined as filling-up, completion and submission of the census schedule by respondents themselves); 'electronic form' takes its meaning from the IT Act, 2000. This amendment is the legal foundation of the digital Census 2027.
• The intent to conduct Census 2027 was notified in the Gazette of India on 16 June 2025 under Section 3 of the Census Act, 1948.
• Related but distinct: NPR is prepared under the Citizenship Act, 1955 and Citizenship (Registration of Citizens and Issue of National Identity Cards) Rules, 2003 — NOT under the Census Act.

Administrative Machinery of Census 2027

Who conducts the census (per PIB Backgrounder's official administrative-setup chart):

• Nodal ministry: Ministry of Home Affairs (MHA), Government of India.
• Head: Registrar General and Census Commissioner of India (RGI) — a single office holding both posts, currently held by an IAS officer of Additional Secretary rank. The current RGI and Census Commissioner is Mritunjay Kumar Narayan, IAS (PIB press conference, August 2025; confidence: high).
• Establishment: the Government of India decided in 1949 to establish a permanent organisation in the MHA under a Registrar General and ex-officio Census Commissioner; before that a census organisation was set up on an ad-hoc basis for each census. (Most UPSC sources cite 1949/1951 for the permanent organisation; Wikipedia says 'founded 1961' — flag this discrepancy; prefer 1949 as per standard sources. Confidence on exact year: medium.) The RGI also runs the Sample Registration System (SRS), Civil Registration System and NPR.
• Chain of command (national): Union Home Minister -> Union Home Secretary -> Registrar General and Census Commissioner of India -> Directors, Directorates of Census Operations (one per State/UT).
• Chain of command (state): Chief Secretary (State/UT) -> Nodal Officer (State/UT) -> Principal Census Officer (DM/DC/Municipal Corporation Commissioner) -> Charge Officer (SDM/Tehsildar/Mamlatdar/BDO/Executive Officer) -> Enumerators and Supervisors (mostly school teachers and state government/local body officials).
• 'Census Moment': the reference point (00:00 hrs of 1 March 2027; 00:00 hrs of 1 October 2026 for snow-bound areas) that decides which persons are to be included in the count.
• The census is centrally coordinated (Union subject) but implemented in close collaboration with State/UT governments.

Two Phases of Census 2027: HLO and Population Enumeration Explained

PHASE I — Houselisting and Housing Census (HLO): 1 April to 30 September 2026. Conducted over 30 days in each State/UT at the state's convenience, with an optional 15-day self-enumeration window immediately before house-to-house work. Collects housing conditions, amenities and assets, and creates the frame for Phase II. The 33 notified questions fall in four blocks (per official PIB graphic): (a) Condition of the house — building/census house number, floor/wall/roof material, use and condition; (b) Household information — persons normally residing, name/sex of head, whether head belongs to SC/ST/Other, ownership status, dwelling rooms, married couples; (c) Amenities — drinking water source and availability, lighting, latrine access and type, waste water outlet, bathing facility, kitchen and LPG/PNG connection, cooking fuel; (d) Assets — radio, TV, internet access, laptop/computer, phone/smartphone, bicycle/scooter/motorcycle, car/jeep/van, main cereal consumed, plus mobile number (for census communication only).

PHASE II — Population Enumeration (PE): February 2027 for most of India (reference date 00:00 hrs, 1 March 2027); September 2026 for UT of Ladakh and snow-bound areas of J&K, Himachal Pradesh and Uttarakhand (reference date 00:00 hrs, 1 October 2026). The 40-question Household Schedule was notified on 14 August 2026 (vs 29 questions in 2011). It covers: name, relationship to head, sex, date of birth/age, marital status, age at marriage, spouse's name, nationality, religion, CASTE (Q10, first time since 1931, alongside SC/ST query), parents' particulars, permanent address, disability, mother tongue and other languages known, literacy and digital literacy, education, economic activity/occupation, migration (duration of stay, reasons), fertility. New (13 new questions) additions include: Aadhaar/passport/driving licence/voter ID numbers (recorded only if available), number of bank accounts (count only), place of COVID-19 vaccination, digital literacy, and mobile number.

Both phases are digital-first: enumerator mobile app (Android/iOS, works offline, 16 languages) with direct field-to-server transmission, or web self-enumeration generating an SE ID that the enumerator later confirms.

Caste Enumeration in Census 2027: First Since 1931

Why it matters for UPSC (GS2 polity + prelims):

• DECISION: Cabinet Committee on Political Affairs (CCPA), meeting of 30 April 2025, decided to include caste enumeration in Census 2027 (PIB — confidence: high). Executed in Phase II (Population Enumeration).
• HISTORY: Every census from 1881 to 1931 recorded caste comprehensively. 1931 (under J.H. Hutton) was the last census whose full caste data was published. The 1941 census collected some caste information but it was not tabulated/published owing to WWII (standard account, confidence: medium). From 1951 onwards, independent India enumerated only Scheduled Castes and Scheduled Tribes, not other castes.
• SECC 2011: the Socio-Economic and Caste Census 2011 (conducted by Ministry of Rural Development/MoHUA, not under the Census Act) collected caste data but the caste numbers were never officially released due to data-quality issues — a favourite mains/prelims contrast: SECC vs Census (legal basis, confidentiality, ministry).
• MECHANICS IN 2027: caste is question 10 of the 40-question PE household schedule, asked alongside whether the person belongs to SC/ST; individual caste (jati) will be recorded; data collected digitally with code directories (Deccan Herald/Millennium Post — confidence: high for question placement).
• SIGNIFICANCE: Mandal Commission's 52% OBC estimate was extrapolated from 1931 caste data; fresh caste data bears on OBC sub-categorisation (Rohini Commission context), reservation policy, and the 50% ceiling debate (analysis point — mark as context, not fact).
• State caste surveys that preceded it: Bihar caste survey 2023, Telangana and Karnataka surveys — useful comparison for mains (confidence: high, widely reported).

History of the Indian Census: 1872 to 2027

Chronology that UPSC loves:

• ANCIENT REFERENCES: Kautilya's Arthashastra (321-296 BCE) prescribed population statistics collection for taxation; Abul Fazl's Ain-i-Akbari (Akbar's reign) contains comparable administrative data (PIB Backgrounder cites both).
• 1865-1872: first modern population count, conducted non-synchronously across regions; culminated in the '1872 census' under Viceroy Lord MAYO — hence 1872 is called India's first (non-synchronous) census.
• 1881: FIRST SYNCHRONOUS decennial census, on 17 February 1881, under Census Commissioner W.C. Plowden, during the viceroyalty of Lord RIPON. Uninterrupted decennial series begins.
• 1911-1921: decade of the only population DECLINE (-0.31%) due to the 1918 influenza pandemic and famines; 1921 is the 'Year of the Great Divide' in India's demographic history.
• 1931: last full caste enumeration (Census Commissioner J.H. Hutton).
• 1941: census affected by WWII; caste data collected but not published (confidence: medium).
• 1948: Census Act enacted (piloted by Sardar Patel).
• 1949: Government decides to create a permanent census organisation under the Registrar General and ex-officio Census Commissioner in the MHA (before this, census organisation was ad hoc per census).
• 1951: first census of independent India (9th in the unbroken series); conducted under the Census Act 1948.
• 1961-2011: censuses every ten years; 2011 was the 15th census (7th after independence), conducted under RGI C. Chandramouli, with 29 PE questions; slogan 'Our Census, Our Future' (slogan: confidence medium, widely cited).
• 2021: census POSTPONED due to COVID-19 — first-ever break in the 1881-2011 decennial chain.
• 2027: 16th census, 8th since independence, first digital, first with caste enumeration since 1931, reference date 1 March 2027.

One-line traps: first census 1872 (not 1881); first SYNCHRONOUS census 1881; Plowden was Census Commissioner (not Viceroy); Great Divide year is 1921 (not 1911); census is decennial by practice, not by constitutional mandate.

Census 2011 Baseline Figures (Comparison Base for 2027)

Census 2011 numbers remain the reference until Census 2027 results arrive — and prelims keeps asking them:

• Total population: 1,210.19 million / 121.09 crore (males 623.72 mn, females 586.46 mn) — PIB release.
• Decadal growth 2001-2011: 17.64% (annual ~1.64%).
• Density: 382 persons per sq km.
• Sex ratio: 943 females per 1,000 males; child sex ratio (0-6): 919 — lowest since independence at the time.
• Literacy: 74.04% overall; male 82.14%, female 65.46%. Kerala highest literacy; Bihar lowest. Most literate district: Serchhip (Mizoram).
• Urbanisation: 31.16% urban.
• Religious composition (2011): Hindus 79.8%, Muslims 14.2%, Christians 2.3%, Sikhs 1.7%.
• Least populous state: Sikkim (~6.1 lakh); highest-density large state comparisons and UT sex-ratio leader Puducherry (1,037) recur in MCQs.
• Administrative units in 2011: 35 States/UTs, 640 districts, 5,990 sub-districts, 4,041 statutory towns, 3,892 census towns, 6,40,932 villages (contrast with 2027: 36 / 784 / 7,092 / 5,128 / 4,580 / 6,39,902).
• 2011 census features: 15th census; two phases (HLO April-September 2010; PE 9-28 February 2011); reference date 00:00 hrs 1 March 2011; 29 PE questions; ~27 lakh enumerators (confidence: medium on enumerator count); C. Chandramouli was RGI.
• Definitions tested repeatedly: Statutory town (notified municipality/corporation/cantonment/town panchayat) vs Census town (population >= 5,000, >= 75% male main workers non-agricultural, density >= 400/sq km); Household = group of persons who commonly live together and take meals from a common kitchen.

Census 2027, Delimitation and Women's Reservation: The Constitutional Chain

The single most exam-relevant linkage of Census 2027:

• ARTICLES: Article 81 (composition of Lok Sabha), Article 82 (readjustment/delimitation after each census), Article 170 (state assemblies), Articles 330/332 (SC/ST reservation of seats). New Articles 330A and 332A (women's reservation) inserted by the 106th Amendment.
• THE FREEZE: 42nd Amendment (1976) froze seat allocation and delimitation on the 1971 census basis until after the first census taken after 2000; the 84th Amendment (2001) extended the freeze until the first census taken AFTER 2026. Census 2027 is precisely that census — the first census after 2026 — so its published figures unlock the next inter-state seat readjustment. (Intra-state boundary adjustment was done on 2001 data by the Delimitation Commission of 2002, without changing state seat totals.)
• WOMEN'S RESERVATION: Constitution (106th Amendment) Act, 2023 — the Nari Shakti Vandan Adhiniyam (passed as the 128th Amendment BILL, September 2023 special session) — reserves one-third of seats in Lok Sabha, state assemblies and the Delhi assembly for women, but takes effect only 'after an exercise of delimitation is undertaken... on the basis of the first census taken after commencement' of the Act. Census 2027 is that first census; hence women's reservation implementation rides on Census 2027 + subsequent delimitation. It is set for 15 years' duration (extendable), with rotation of reserved seats after each delimitation.
• 2026 CURRENT AFFAIRS TWIST: the Constitution (131st Amendment) Bill, 2026 and the Delimitation Bill, 2026 — introduced in Lok Sabha on 16 April 2026 — sought to let Parliament choose the census for delimitation, use CENSUS 2011 data (raising Lok Sabha's cap from 550 to 850 seats: UP +9, Bihar +6, Tamil Nadu -7, Kerala -5), and de-link women's reservation from the post-2026 census. The 131st Amendment Bill was NEGATIVED on 17 April 2026 (Wikipedia says it fell short by 56 votes — confidence: medium on margin), and the Delimitation Bill became infructuous (PRS). Consequence: the original position stands — delimitation and women's reservation await Census 2027 data, and are widely expected to slip past the 2029 general election (analysis, confidence: high as reported).
• Also linked to census figures: Finance Commission devolution weights, SC/ST seat reservation shares, and parliamentary constituency populations.

NPR and Census 2027: What Is and Is Not Confirmed

NPR facts for prelims (with careful confidence flags):

• WHAT NPR IS: the National Population Register is a register of 'usual residents' of India — a usual resident is a person who has resided in a local area for the past 6 months or more, or intends to reside there for the next 6 months or more. It is prepared under the Citizenship Act, 1955 and Citizenship Rules, 2003 — NOT the Census Act — and includes both citizens and non-citizens who are usual residents.
• HISTORY: first prepared in 2010 alongside Census 2011 houselisting; updated in 2015 (Aadhaar/mobile seeding); the December 2019 Cabinet approved Rs 3,941.35 crore (about Rs 39.41 billion) for an NPR update planned with Census 2021 houselisting — that update never happened because Census 2021 was postponed (COVID-19 and protests context).
• STATUS FOR CENSUS 2027 — UNCONFIRMED: as reported from a preparatory meeting of Census Directors (3-4 July, reported 2026), the Centre had NOT yet formally decided whether NPR will be updated during Census 2027. Some reports say NPR update is expected alongside houselisting (its first refresh since 2015) with a self-updating web facility after authentication; treat any claim that 'NPR is being updated in Census 2027' as confidence: unconfirmed until an MHA/PIB notification says so. What IS confirmed: NPR remains maintained by the RGI, and no NPR schedule was part of the 33 notified HLO questions of January 2026.
• KEY DISTINCTIONS TABLE (prelims staple): Census (Census Act 1948, confidential, statistical, MHA/RGI) vs NPR (Citizenship Rules 2003, identity register of usual residents, RGI) vs Aadhaar (UIDAI, Aadhaar Act 2016, voluntary enrolment ID) vs SECC (executive survey, data shareable with departments).

Digital Infrastructure of Census 2027: CMMS, Apps and Portals

The four-plus digital pillars (soft-launched by Union Home Minister Amit Shah on 5 March 2026, per newsonair/DD News; detailed in the PIB Backgrounder):

1. CMMS PORTAL — Census Management and Monitoring System: integrated dashboard for managing and monitoring the entire census on a near-real-time basis at sub-district, district, state and national levels.
2. HLO MOBILE APP: secure app for enumerators (Android and iOS) to collect and upload houselisting data; works in 16 regional languages; offline-capable; accessible only to those registered on CMMS; direct field-to-server transmission eliminating paperwork.
3. HLBC — Houselisting Block Creator: web mapping application for Charge Officers; digital creation of houselisting blocks using SATELLITE IMAGERY, ensuring geographic coverage without omission or duplication (geo-referenced jurisdictions).
4. SELF-ENUMERATION PORTAL (https://se.census.gov.in/): web facility in 16 languages (Assamese, Bengali, English, Gujarati, Hindi, Kannada, Konkani, Malayalam, Manipuri, Marathi, Nepali, Odia, Punjabi, Tamil, Telugu, Urdu) where households submit their own information during the 15-day pre-visit window; generates a unique Self-Enumeration ID (SE ID) which the enumerator uses to confirm the data during the field visit. Vice-President C.P. Radhakrishnan filled his self-enumeration form online on 1 April 2026 (newsonair). Over 82 lakh households had used the portal by mid-August 2026.

SECURITY: end-to-end encryption across collection, transmission and storage; data hosted in certified data centres designated Critical Information Infrastructure (CII) under the IT Act; ISO/IEC 27001:2022-compliant systems with regular security audits.

MASCOTS: 'Pragati' (female enumerator) and 'Vikas' (male enumerator) — official Census 2027 mascots unveiled by HM Amit Shah, developed by C-DAC; they symbolise equal participation of women and men (drishti/newsonair; possible prelims one-liner).

Census 2027 Progress Tracker Facts (as of 1 September 2026)

Where the exercise stands right now (useful for interviews and current-affairs prelims):

• Phase I (HLO) is in its FINAL month (window closes 30 September 2026). As of mid-August 2026, houselisting had been COMPLETED in 31 States/UTs, with the remainder scheduled to finish by September (ANI, confidence: high).
• Field operations began on 1 April 2026 in six States/UTs (newsonair), with other states taking their 30-day windows through the summer.
• Around 82 lakh households had used the Self-Enumeration Portal by mid-August 2026 (up from 5.72 lakh on 10 April 2026).
• LADAKH: completed HLO 1-30 June 2026 with 100% digital data collection across 579 blocks in 17 charges; ~637 enumeration blocks created for Population Enumeration; snow-bound self-enumeration ran 17-31 August 2026; Population Enumeration for Ladakh and snow-bound areas of J&K/HP/Uttarakhand runs 1-30 SEPTEMBER 2026 (i.e., it began today, 1 September 2026), against reference date 00:00 hrs of 1 October 2026. Ladakh is set to become the first UT to complete Census 2027.
• Phase II Household Schedule (40 questions) was notified on 14 August 2026; PE for the rest of India follows in February 2027, reference date 00:00 hrs of 1 March 2027.
• Note for content freshness: verify the '31 States/UTs completed' figure against later PIB releases as September closes.

20 Most Common Census Questions in UPSC and PSC Prelims (with Answers)

Compiled from verified past papers and the recurring question bank across UPSC/state-PSC/SSC compilations (Testbook census MCQ bank, UPSC 2011 paper, Drishti/coaching compilations). Q7 is a verbatim-verified UPSC PYQ; the rest are the most-repeated question patterns with their settled answers — note: except Q7, treat these as recurring THEMES, not verbatim UPSC questions.

1. In which year was the first census conducted in India? — 1872 (non-synchronous, under Lord Mayo).
2. When was the first synchronous/complete decennial census held? — 1881, under Census Commissioner W.C. Plowden, Viceroy Lord Ripon (17 February 1881).
3. Which year is called the 'Year of the Great Divide' in India's demographic history? — 1921 (only census decade with population decline, about -0.31%, due to the influenza pandemic).
4. Census falls under which list of the Seventh Schedule? — Union List, Entry 69 (Article 246).
5. Under which law is the census conducted? — Census Act, 1948 (piloted by Sardar Vallabhbhai Patel); operationalised by Census Rules, 1990 (amended 2022 for digital/self-enumeration).
6. Who conducts the census? — Registrar General and Census Commissioner of India, Ministry of Home Affairs (permanent organisation since 1949; also runs SRS and NPR).
7. [UPSC CSE 2011 — VERIFIED PYQ] 'India is regarded as a country with Demographic Dividend. This is due to:' — Answer: its high population in the age group of 15-64 years.
8. Census 2011 was the ___th census? — 15th overall, 7th after independence. (Census 2027 = 16th and 8th.)
9. Literacy rate as per Census 2011? — 74.04% (male 82.14%, female 65.46%); a person aged 7+ who can read and write with understanding is 'literate'.
10. Sex ratio and child sex ratio (2011)? — 943 and 919 per 1,000 males; best UT sex ratio: Puducherry (1,037); Kerala best among states.
11. Population density (2011)? — 382 persons/sq km.
12. Decadal growth 2001-2011? — 17.64% (annual ~1.64%); total population 121.09 crore.
13. Highest/lowest literacy states? — Kerala highest; Bihar lowest. Least populous state: Sikkim.
14. How does the census define a household? — a group of persons normally living together and taking food from a common kitchen.
15. Distinguish statutory town and census town — statutory: notified municipality/corporation/cantonment; census town: population >= 5,000, >= 75% of male main workers non-agricultural, density >= 400/sq km.
16. When was caste last fully enumerated? — 1931 (Census 2027 resumes caste enumeration; CCPA decision of 30 April 2025; SECC 2011's caste data was never released).
17. Which amendments froze delimitation, and until when? — 42nd Amendment (up to the first census after 2000) and 84th Amendment (up to the first census after 2026) — hence Census 2027 triggers the next readjustment (Articles 81, 82, 170).
18. What does the 106th Amendment (Nari Shakti Vandan Adhiniyam, 2023) provide? — one-third reservation for women in Lok Sabha/state assemblies/Delhi, effective only after delimitation based on the first census taken after its commencement (i.e., Census 2027); 15-year initial duration.
19. Census 2027 basics — 16th census; first digital census; first with self-enumeration; two phases (HLO Apr-Sep 2026; PE Feb 2027); reference dates 1 March 2027 and 1 October 2026 (snow-bound); outlay Rs 11,718.24 crore; ~31 lakh enumerators; 33 HLO + 40 PE questions; app in 16 languages.
20. Is census data admissible in court or under RTI? — No; Section 15 of the Census Act 1948 makes individual records confidential, non-admissible as evidence and outside RTI — while NPR/Aadhaar operate under different laws (Citizenship Rules 2003 / Aadhaar Act 2016).

Census 2027 One-Liner Revision Capsule (Prelims Rapid Fire)

Rapid-revision one-liners, each independently sourced:

• Census 2027 = 16th Indian census, 8th since independence, FIRST digital, FIRST with self-enumeration, FIRST caste count since 1931.
• Gazette notification of intent: 16 June 2025 (Census Act 1948, Section 3).
• Reference date: 00:00 hrs, 1 March 2027; snow-bound areas (Ladakh + parts of J&K, HP, Uttarakhand): 00:00 hrs, 1 October 2026. This instant is the 'Census Moment'.
• Phase I HLO: 1 April - 30 September 2026 (30 days per State/UT + optional 15-day self-enumeration window); 33 questions.
• Phase II PE: February 2027 (September 2026 for snow-bound); 40 questions (2011 had 29); caste at Q10; notified 14 August 2026.
• Outlay: Rs 11,718.24 crore (Cabinet, 12 December 2025).
• Workforce: ~31 lakh enumerators/supervisors + 1 lakh+ functionaries; mostly school teachers.
• Tech: CMMS portal, HLO mobile app (16 languages, Android/iOS, offline), HLBC satellite-imagery block mapping, Self-Enumeration Portal se.census.gov.in with SE ID; data centres are Critical Information Infrastructure; ISO/IEC 27001:2022.
• Admin frame frozen 1 January 2026: 36 States/UTs, 784 districts, 7,092 sub-districts, 5,128 statutory towns, 4,580 census towns, 6,39,902 villages (villages FELL vs 2011 — trap).
• Mascots: Pragati and Vikas (C-DAC); unveiled by Amit Shah, March 2026.
• RGI and Census Commissioner: Mritunjay Kumar Narayan, IAS; ministry: MHA; office permanent since 1949.
• Legal chain: Entry 69 Union List -> Census Act 1948 -> Census Rules 1990 -> Census (Amendment) Rules 2022 (digital + self-enumeration; notified 11 March 2022).
• Confidentiality: Section 15, Census Act — not admissible in court, outside RTI.
• Delimitation: 84th Amendment freeze ends with the first census after 2026 = Census 2027; women's reservation (106th Amendment, 2023) waits on delimitation based on this census; the 131st Amendment Bill and Delimitation Bill 2026 that tried to switch to 2011 data were defeated/infructuous on 17 April 2026.
• Caste decision: CCPA, 30 April 2025.
• History hooks: Arthashastra and Ain-i-Akbari references; 1872 Lord Mayo; 1881 Lord Ripon/W.C. Plowden; 1921 Great Divide (-0.31%); 1948 Act piloted by Sardar Patel; 1951 first post-independence census; 2021 census skipped (COVID-19) — longest gap (16 years) in the series.
• Employment: ~1.02 crore man-days generated; ~18,600 technical staff for ~550 days.
• Results expected: provisional late 2027, final around 2028 (unconfirmed — no official date announced).