Decoding the impact of SIR in West Bengal

The BJP’s victory in West Bengal has evoked strong reactions across the political spectrum, from celebratory appreciation to profound shock and disbelief. While the winners, led by Prime Minister Narendra Modi, claimed it was an anti-incumbency mandate for change, defeated former chief minister Mamata Banerjee complained of electoral rigging and foul play. The truth seems to lie somewhere in between.

Double Impact: SIR & Polarization

The two-phase parliamentary elections in West Bengal saw an unprecedented voter turnout of over 93%, compared to 82% in the 2021 Assembly elections and 79% in the 2024 Lok Sabha elections. This 93% figure, apparently the highest ever recorded in a general election in any major Indian state, was inflated by a low base effect because the electorate has shrunk by around 80,000 million voters after the Special Intensive Revision (SIR) of electoral rolls in West Bengal.

The SIR exercise began in West Bengal along with 11 other states and UTs on 4 November 2025. Although initially scheduled to be completed by the end of January 2026, the Election Commission of India (EC) introduced a new criterion of “logical discrepancy”, only in West Bengal, to identify and remove more voters from the electoral roll. This led to an extended process of hearings, judicial intervention, adjudication and ultimately the Appellate Tribunal process, which continues to this day and is likely to continue for several years to come. Courts of appeal are said to be awaiting more than 34,000 appeals.

Mass deletion of voters on an unprecedented scale, together with a significant number of non-transparent additions, had a major impact on the demographic composition of the lists. This appears to have decisively influenced the election results, in addition to significant anti-establishment and communal polarization.

While the total number of voters in West Bengal decreased from 7.34 million in 2021 to 6.81 million in 2026, the total number of valid votes increased from around 6.03 million to 6.37 million. The total number of votes in favor of the All India Trinamool Congress (AITC) fell from 2.89 million in 2021 to 2.60 million in 2026, a decrease of 29.5 million votes. In contrast, the BJP’s total poll vote increased by 63 lakh, from 2.29 million in 2021 to 2.92 million in 2026. The total vote and vote share of the CPI(M) and the Congress remained roughly the same (Table 1).

The relative magnitude of each component of the dual impact of SIR and anti-incumbency-cum-polarization can only be understood in terms of the religious-demographic distribution of SIR deletions. Since the EC does not store or publish religio-demographic data on voters, this analysis relied on digital scrutiny of electoral rolls and deletion lists for the high-profile Bhabanipur constituency, where the BJP’s Suvendu Adhikari defeated Ms Banerjee. In the absence of other reliable data from recent years, the 2011 census was used to calculate the estimated population of Muslims at the district and state levels.

The deletions under SIR in West Bengal occurred in three phases viz. enumeration; claims and objections; and decision making. Of the total 58.2 lakh ASDD (Absent, Shifted, Deceased, Duplicate) deletions in the first phase, 32 lakh were classified as Absent or Shifted. A digital check of the ASDD rolls revealed that roughly 7.34 lakh (23%) of the absentee or displaced voters were Muslims. Of the 27.16 million voters struck out after the verdict, which were mainly cases of “logical discrepancy” (LD), roughly 17.65 million (65%) were Muslims (Table 2).

Thus, of the total 64.7 million nationwide aggregated SIR deletions, excluding deletions in the Deceased and Duplicate categories, over 25 million were Muslims, i.e. 38.6%, higher than their 27% share in the 2011 Census population.

Nationwide SIR Impact Analysis

Impact analysis of a total of 67.26,000,000,000,000,000,000,000,000,000 SIR changes defined as the sum of deletions in Absent, Shifted, and LD cases and additions during SIR was performed by a team of experts. Chart 1 shows the district-wise distribution of these SIR changes, along with the district-wise proportions of the projected size of the Muslim electorate, calculated using the district percentage of the Muslim population as reported in the 2011 census. This brought the estimated number of Muslim voters to 1.77 million (26%) out of a total electorate of 6.81 million.

Chart 1 clearly shows that the number of SIR changes (deletions in three categories and additions as explained earlier) was much higher in 12 districts with higher concentration of Muslims, namely North 24 Parganas, Kolkata, Murshidabad, South 24 Parganas, Howrah, Malda, Hoogly, Nadia, Purba Bardhaman, Paschim Bardhumnaj and Ut Bardhuman These 12 accounted for more than 84% Muslims. voters, also accounted for more than 80% of the SIR changes.

Since six of these districts share no international border with Bangladesh, the higher changes in SIR cannot be easily explained in terms of suspected cross-border irregular migrants. Rather, it appears that the entire minority population in Muslim concentrated districts was suspect during the SIR process. This is confirmed by the findings of independent studies reported in the mainstream media, which stated that at least 37% of the total deletions under the SIR were Muslims.

Analyzing the results in terms of AC shows that of the 207 seats won by the BJP in 2026, the magnitude of SIR changes exceeded the BJP’s winning margin in 82 seats. Of these, 70 were located in 12 concentrated Muslim districts. In 2021, BJP won only 9 of these 82 ACs. In 2026, SIR changes appear to have decisively influenced the election outcome in these 82 ACs. In other words, it is not unlikely that the BJP could not secure a majority in the West Bengal Assembly elections without the impact of SIR.

SIR impact in Bhabanipur

This pattern of disproportionate deletion of Muslim voters, which may affect the results, is evident in Bhabanipur constituency, where a digital check of the ASDD and polling station voter lists revealed that out of a total of 36,664 deletions in the Absent, Shifted and LD categories, 9,481 (26%) 2 were Muslims (Table). This share of 26% is significantly higher than the 20% share of Muslims in the population of Calcutta district in 2011. These discharges of Muslim voters were highly concentrated in wards 1 to 112 (polling stations), falling under wards 63, 77 and 74 of the Kolkata Municipal Corporation with a high concentration of Muslim population.

Moreover, while Muslims accounted for 26% of the deleted entries, they accounted for only 19% (1,025) of the 5,408 additions to the electoral rolls of Bhabanipur.

The AITC’s margin of victory over the BJP in the Bhabanipur assembly segment has already fallen from 58,835 in the 2021 by-election, in which Ms Banerjee won with a 72% vote share, to 8,297 in the 2024 Lok Sabha election.

The net loss of Muslim voters (total cuts without additions) in Bhabanipur AC during SIR was 8,456.

In the 2026 elections, Bhabanipur recorded 5,524 more valid votes than in 2024, which incidentally is a similar range to the total gain during SIR at 5,408.

Between 2024 and 2026, the votes secured by the AITC fell by 3,649, while those of the BJP increased by 19,753 (Table 3).

In addition, between the two elections, the votes polled by the CPI(M) decreased by 10,540 and the votes of all others by 1,448. It is likely that these votes went in favor of the BJP in 2026 instead. However, such a swing in BJP’s favor in the constituency is unlikely to have happened if not for the SIR that reconfigured the demographics.

This raises new questions about the intent and legitimacy of the SIR, which deserve to be remedied by the Supreme Court to prevent repetition in other states. The dysfunctional and ineffective appeals mechanism in West Bengal needs to be strengthened to ensure justice for all who have been wrongfully erased through opaque, discriminatory and arbitrary processes.

The EC should be held accountable for conducting the SIR in a manner that not only led to mass disenfranchisement of genuine voters on the eve of general elections, but also threatened the future of free and fair elections in a country that is the cornerstone of parliamentary democracy. The European Commission must publish a comprehensive statistical report on all SIR data on deletions, additions and amendments to electoral rolls in West Bengal not yet officially reported to facilitate further independent analysis and judicial review.

Prasenjit Bose is an economist. He heads the SIR committee of the West Bengal Pradesh Congress Committee