Mod 7: Base Year, Constant Prices & Revisions of India’s National Accounts (to 2022-23)

📖 Chapter 2 🧩 Module 8 of 16 ⏱️ ~5 min read 💡 20 MCQs

Topic Part 1 of 2

Concept

7.1 What a base year is and why it is revised

🏫 School level · NCERT Class 9–12 (the base for UPSC, BPSC, SSC and Bank exams)

Base year = the price year for real GDP

Real GDP needs a ruler that does not stretch every year. The base year is that ruler: the year whose prices are used to value the quantities of later years. It is the year whose prices are used to calculate real GDP, not nominal GDP.

A good base year is a normal year (no drought, war or crisis), has reliable data, and is not too far in the past. As the economy changes (agriculture’s share falls, services and new industries grow), an old base gives wrong weights, so the base is revised about once a decade.

Fig 7.1 India’s base years. Questions written in 1999, 2009, 2010, 2015 or after 2026 each have a different correct answer.

Table 7.1 Which base answers which question?
Question set around	Base year in use
February 1999 release	1993-94
2009	1999-2000
2010–2014	2004-05
2015–2025	2011-12
After February 2026	2022-23

Worked example

A price index is 100 in the base year and 125 now. By how much have prices risen? If nominal output is ₹500 crore now, what is it at base-year prices?

Rise = (125 − 100) ÷ 100 = 25%.
Real value = 500 ÷ 125 × 100 = ₹400 crore.

Prices up 25%; real output ₹400 crore

⭐ Key Points for Exams

Base year = year whose prices value real GDP.
Choose a normal, recent year with good data; revise as structure changes.
Sequence: 1993-94 → 1999-2000 → 2004-05 → 2011-12 → 2022-23.

📌 Quick-Fire One-Liners

Current base year (after Feb 2026)? Answer: 2022-23
Index 125, nominal ₹500 cr: real value? Answer: ₹400 crore

Topic

Questions

MCQs

Answer this question, then use Next.

Changing the base year of national accounts mainly changes:

Explanation: A base revision replaces the price rod and the weights. It does not redefine the territory or depreciation.

[School] A base year for national accounts should preferably be:

Prices and structure in the base year are used as weights for many years, so an abnormal year would distort every later real figure. Reliable data and recency also matter.

[UPSC level] After the February 2026 revision, the base year of India’s national accounts is:

The NSO’s new series released in February 2026 uses 2022-23 prices; FY 2025-26 estimates are on this base. 2011-12 was the base from 2015 until then.

[School] The main reason for periodically revising the base year is:

Agriculture’s share falls, services and new products rise; a base that still uses old shares misstates growth. The revision may raise or lower measured growth.

[Numerical] A price index is 125 with base year = 100. Nominal output is ₹500 crore. Output at base-year prices is:

Real = nominal ÷ index × 100 = 500 ÷ 125 × 100 = ₹400 crore. Multiplying by 1.25 (₹625 crore) would inflate rather than deflate.

[School] Which is the correct chronological order of base years in India?

Earlier bases were 1948-49, 1960-61, 1970-71 and 1980-81; then 1993-94 (1999), 1999-2000, 2004-05 (2010), 2011-12 (2015) and 2022-23 (2026).

Question 1 of 6

One-liners

Write your answer, then submit to see the correct answer.

Current base year (after Feb 2026)?

2022-23

Index 125, nominal ₹500 cr: real value?

₹400 crore

Question 1 of 2

Topic Part 1 of 2

Concept

7.2 The 2015 overhaul, the 2026 rebase and linking series

🏫 School level · NCERT Class 9–12 (the base for UPSC, BPSC, SSC and Bank exams)

2015: base and method; 2026: base 2022-23

The January 2015 revision did two things at once: it moved the base from 2004-05 to 2011-12, and it changed the method, from GDP at factor cost to GVA at basic prices, in line with the UN System of National Accounts (SNA) 2008. It also used the Ministry of Corporate Affairs’ MCA-21 database of company filings for the corporate sector. So the right answer to “what changed in 2015?” is both the base year and the method.

In February 2026 the NSO released a new series with base year 2022-23; the FY 2025-26 estimates (real growth 7.8%, nominal 8.6%) are on this base. Older exam questions keep their own keyed years.

📐 Comparing series with different bases

A new base changes prices, weights and coverage, so growth rates from two bases are answers to slightly different questions.
Before comparing, the statistical office links the series at an overlap year or publishes a back series (old years recomputed on the new base and method).
Some countries use chain-linking: weights are updated every year, so there is no single fixed base.
A newer base does not automatically mean higher growth; it can raise or lower it.

⭐ Key Points for Exams

2015: base 2004-05 → 2011-12 AND method → GVA at basic prices (SNA 2008); MCA-21 data.
Link series or use a back series before comparing growth across bases.
Chain-linking updates weights every year.

📌 Quick-Fire One-Liners

What changed in the 2015 revision? Answer: Both the base year and the method
Which database covers company accounts? Answer: MCA-21

Topic

Questions

MCQs

Answer this question, then use Next.

A growth rate from a 2004-05 base series and a growth rate from a 2011-12 base series should be compared directly only when:

Explanation: Different base years use different weights. A linking factor at an overlap year puts them on one ruler. A higher base year does not by itself mean a higher growth rate.

Real growth in a national-accounts series is the change in:

Explanation: Real growth holds the price rod still, so it uses constant prices of the base year. Current prices mix in inflation. The base year is the rod, not the thing being measured.

[SSC pattern] The System of National Accounts (SNA) 2008 is an international framework of the:

SNA 2008 is the UN statistical standard for national accounts, prepared jointly with the IMF, World Bank, OECD and the European Commission (Eurostat). India aligned with it in 2015.

[RBI Grade B level] Basic price is:

Basic price is what the producer receives: it includes production taxes net of production subsidies, but not product taxes such as GST. Adding net product taxes gives market price.

[Bank PO pattern] The 2011-12 series used which database for estimating the corporate sector?

MCA-21 contains the filed accounts of companies, allowing a fuller picture of corporate value added than the older sample of RBI company studies. Its use was one reason the new series differed from the old.

[RBI Grade B level] “Chain-linking” of national accounts means:

Chain-linked indices avoid the problem of an ageing base by using the previous year’s prices each year; many developed countries use them.

[UPSC level] A “back series” of GDP means:

Without a back series, growth rates before and after a rebase are not comparable. India published back series for the 2011-12 base in 2018.

Question 1 of 7

One-liners

Write your answer, then submit to see the correct answer.

What changed in the 2015 revision?

Both the base year and the method

Which database covers company accounts?

MCA-21

Question 1 of 2

Topic Part 1 of 2

Concept

🎯 Competitive Level (UPSC Pre · BPSC Pre · State PSC · SSC · Bank PO · RBI Grade B): Base years in past papers

Exam map
Exam	What it asks from this module
UPSC Prelims	base of the 1999 series (2000)
BPSC / State PSC	meaning of base year (RAS 2021); what changed in 2015 (RAS 2013); base years asked by UPPSC 2009, 2010, 2015, 2016
SSC / Railways	current base year, SNA
Bank PO / RBI Grade B	GVA at basic prices, back series, chain-linking

🏆 Previous Year Question · R.A.S./R.T.S. (Pre) 2021

R.A.S./R.T.S. (Pre) 2021

“Base year” in National Income accounting means: (a) the year whose income is being used to calculate the nominal GDP (b) the year whose prices are being used to calculate the nominal GDP (c) the year whose prices are being used to calculate the real GDP (d) the year whose income is being used to calculate the real GDP

Nominal GDP uses each year’s own prices, so it needs no base.
Real GDP values current quantities at the prices of the base year.

⭐ Key Points for Exams

RAS 2021: base year = year whose prices calculate real GDP.
UPPSC 2009 → 1999-2000; 2010 → 2004-05; 2015/16 → 2011-12.

📌 Quick-Fire One-Liners

Base of the CSO series released in February 1999? Answer: 1993-94

Topic

Questions

MCQs

Answer this question, then use Next.

Question 50: 'Base year' in National Income accounting means: [R.A.S./R.T.S. (Pre) 2021]

Explanation: Base year refers to the benchmark reference period whose constant prices are used to value current physical goods and compute real GDP.

Question 51: Indicate the vital change in the measurement of National Income of India recently: [R.A.S./R.T.S. (Pre) (Re-Exam) 2013]

Explanation: CSO altered the base year from 2004-05 to 2011-12 and adopted GVA at basic prices under UNSNA 2008, meaning both the base year and calculation method were overhauled.

Question 52: In new GDP data, base year has been changed from 2004-05 to: [U.P.P.C.S. (Mains) 2015]

Explanation: The national accounts series was revised in January 2015 by updating the reference base year from 2004-05 to 2011-12.

Question 53: At present (2015) which of the following base year is being used for estimation of National Income in India? [U.P.P.C.S. (Mains) 2016]

Explanation: Following the 2015 revision, the base year applied for constant price GDP estimation was 2011-12. The new series (January 2015) moved the base from 2004-05 to 2011-12 and introduced GVA at basic prices.

Question 54: In India for estimation of GDP at constant prices, at present the base year is: [U.P.P.C.S. (Pre) 2009]

Explanation: During the 2009 examination period, the CSO was using 1999-2000 as the base year (later shifted to 2004-05, and subsequently to 2011-12).

Question 55: Which of the following is the correct base year for measuring National Income in India? [U.P. U.D.A./L.D.A. Spl. Pre 2010]

Explanation: In January 2010, the CSO updated the national accounts series from 1999-2000 to the 2004-05 base year. Sequence of bases used in exams: 1993-94 (1999), 1999-2000, 2004-05 (2010), 2011-12 (2015), 2022-23 (February 2026).

Question 56: The new GDP series released by the CSO in February, 1999 is with reference to base prices of: [I.A.S. (Pre) 2000; U.P.P.C.S. Mains 2004]

Explanation: The national accounts series unveiled by the CSO in February 1999 used 1993-94 as the base year. Each rebase updates prices and weights to reflect the current structure of the economy; answer from the date of the question.

Question 1 of 7

One-liners

Write your answer, then submit to see the correct answer.

Base of the CSO series released in February 1999?

1993-94

Question 1 of 1