The Calcutta Municipal Corporation (CMC) has been losing around Rs 30 crore annually on these plots as the owners are claiming they are yet to get ownership rights or pattas from the government.

In the civic assessment records, most colony plots are still mentioned as government or colony land though over the past 35 years, the refugee rehabilitation department has distributed 7,500 bighas among the settlers, most of whom came from the erstwhile East Pakistan.

Unless the residents are officially notified as owners, they cannot be brought within the tax net. “Even the owners of colony plots on which highrises have come up are claiming that they do not officially own the land,” said a civic assessor and collector.

More than a lakh people who have bought flats on colony plots in east Calcutta, Jadavpur, Santoshpur, Garia, Behala, Dhakuria, Bagha Jatin and Beleghata cannot get their properties mutated in their names because of the “ownership dispute”.