Discuss the rationale and challenges involved in periodic revision of the base year for India's National Accounts Statistics.

A base year fixes the prices, weights and data sources on which the entire national accounts series rests. MoSPI's shift of the GDP base from 2011-12 to 2022-23 [1] makes periodic revision — and its accompanying "Sources and Methods" documentation — a live question of statistical credibility.

Rationale for periodic revision

• Capturing structural change: an economy measured with 2011-12 weights under-counts activities that barely existed then — digital platforms, IT/ITES, delivery services. The new series adopts the latest NIC-2025 classification covering the full service sector [1].
• Choice of a normal benchmark year: 2022-23 was selected as a post-COVID normal year with robust cross-sectoral data, unlike the distorted 2020-21 [1].
• Better measurement of the informal sector: the household/unincorporated sector, earlier extrapolated through proxy indicators, is now estimated annually from ASUSE and PLFS survey data [2].
• Richer administrative sources: GST outward taxable supply and the MCA-21 corporate database replace survey-only estimates, improving granularity and quarterly timeliness [2].
• Technical refinement: Proportional Denton benchmarking replaces the pro-rata method, removing artificial year-end breaks in the quarterly series [2].

Challenges involved

• Comparability across the break: older years must be recomputed or spliced; in the 2011-12 revision the back series diverged enough to require a formal government clarification [3].
• Formalisation mistaken for growth: a firm entering the GST net adds visibility, not output — unless separated, wider tax coverage can inflate measured value added [2].
• Recalibration of fiscal ratios: deficit and debt-to-GDP change without any change in government behaviour [1].
• Upstream data quality: the National Statistical Commission flagged that unit-level data at times did not match published summary tables [4].
• Weak institutional guardianship: the NSC rests on a 2005 executive resolution, so its concerns are advisory, not binding [4].

Base-year revision is therefore necessary hygiene, not manipulation; the risk lies in careless comparison across the break. Publishing the back series alongside the new one, quantifying the formalisation effect, giving the NSC statutory backing, and institutionalising the pre-release public consultation already used this cycle [5] would convert a technical exercise into a durable source of public trust.