Changing the GDP base year is not just about changing how we calculate economic growth. It can also change our estimate of how large the economy was in rupee terms — what is known as nominal GDP. When one gets a better picture of the economy through new data, improved methods and wider coverage, our understanding of the economy has to be reviewed. Importantly, as recognised in international statistical practice, such revisions do not necessarily move in one direction: the estimated size of the economy can go up or down, depending on what new data, methods reveal.

With the recent base revision of GDP, across the three years for which both series overlap, India’s nominal GDP was revised down by about 2.7% in 2022-23, 3.5% in 2023-24 and 3.8% during 2024-25. However, India is not alone in seeing nominal GDP estimates change when the GDP base is revised. Rebasing exercises in countries such as Nigeria (2014), Indonesia (2014), Brazil (2015), South Africa (2018), Mexico (2019), China (2021) and Spain (2024) all resulted in revisions to previously estimated nominal GDP levels. India’s earlier shift from base year 2004-05 to the 2011-12 also changed the estimated size of the economy. The important question, therefore, is not simply why the number changed, but what changed in our data or methods which led to the new number.

It is worthwhile to mention that the Press Release dated February 27, 2026 on the New GDP Series with base year 2022-23 had already indicated the various methodological improvements and updated data sources which contributed to revisions in the nominal GDP, along with a comparative table indicating economic activity wise revisions and the reasons for such revisions.

Much of the media attention has focused on the headline downward revision in GDP, while overlooking the substantial upward revisions in several sectors. A proper assessment requires looking at the sector-wise picture, where the revisions are far from uniform. Agriculture and allied activities were revised up by about 3.8%–5.9%, while financial services and real estate, professional services and ownership of dwellings were revised up by roughly 7.8%–9.0% over comparable years. In contrast, trade and transport and storage saw sharp downward revisions of around 23%–26%. Trade GVA (Gross Value Added) was revised downwards by 36%, road transport by 16.9%, whereas hotels and restaurants’ GVA was revised upwards by 5.7%, mainly on account of the revised estimates of the unincorporated sector. In the 2011-12 series, this sector was estimated by moving forward benchmark estimates with proxy indicators whereas in the new series, ASUSE (Annual Survey of Unincorporated Sector Enterprises) and PLFS (Periodic Labour Force Survey) data provided a more direct basis for measurement of the unincorporated sector.

Therefore, a major driver of the revision in nominal GDP in the case of India is the improved measurement of India’s unincorporated services sector. The World Bank’s April 2026 India Development Update similarly notes that India’s nominal GDP was revised down by 3–4% in each of the four years from FY23, mainly due to a reassessment of the informal economy. It also notes that the revised series shows quarterly growth between FY 2023-24 to FY 2025-26 to be less volatile and more broad-based than previously estimated. However, it has to be noted that revisions in the unincorporated sector have not been uniformly revised but vary sector to sector. Moreover, India’s quarterly and provisional GDP estimates are built from the previous year’s quarterly figures and then updated using information such as GST collections and industrial production. So, when the FY 2022-23 GDP estimate was revised under the new methodology, the change naturally carried forward into the years that followed and all subsequent annual and quarterly estimates moved down with it. This does not mean the economy suddenly became smaller or slowed down in those years; part of the change reflects that we are now starting the calculation from a different, better-measured number.

Ultimately, the new GDP series should be judged not by a single headline revision, but by the effort to make the measurement of the Indian economy more current. The real test of a statistical system is not whether its numbers remain unchanged, but whether it is willing to change them when better evidence becomes available.

Saibal Chattopadhyay is Chairman, National Statistical Commission; Saurabh Garg is Secretary, Ministry of Statistics and Programme Implementation