The Calcutta Municipal Corporation has finally replaced the notional rent value system for property tax calculations with the “more scientific” unit-area method of assessment that promises to lower the tax burden on the middle class.

A gazette notification announcing the switch will be made on Friday, a source in the civic headquarters said. Once the notification — which does not include the rates for respective areas — are issued, house-owners will get 60 days to file their objections and suggestions, if any.

“The switch is a must as international funding agencies wanted us to adopt the unit-area system,” said a civic official. Delhi and Ahmedabad have already adopted the new system.

Metro had reported in June that the 187-sq km of the city area has been divided into seven zones (A-G), which have further been split into 262 blocks. Property tax will be the highest in Zone A and the lowest in Zone G.

Only nine wards (42, 45, 46, 49, 61, 63, 70, 71 and 74) in the city proper have been placed in Zone A, where the property tax has been fixed at Rs 4-5 per square foot. The localities include Burrabazar, Dalhousie, Chandni Chowk, Bowbazar, Park Street, Camac Street, Rawdon Street, Loudon Street, Bhowanipore, Gariahat and Rashbehari Avenue.

Of the 41 wards in the added areas of Behala, Garden Reach and Jadavpur, 31 are in zones E to G, where the property tax has been fixed from Rs 1.4 to Rs 1.7 per square foot.

The Trinamul board claims middle-class people who have flats will benefit from the new system.