your final entitlement is legally bound to the certified physical area under active occupancy, as verified and formalised by the BMC in the official Annexure-II (Eligibility List). The developer has no legal authority to decide what constitutes an "illegal old extension" or truncate your area on their own accord.

2) The Bombay High Court has consistently ruled that in cases of redevelopment disputes regarding tenement sizes, the municipal corporation (BMC) must measure and certify the official area under occupation. The developer cannot take the law into their own hands to deduct area based on their internal, subjective classification of an "extension".

you can seek phone consultation in case you need further clarifications

Dear Sir/Madam,

BMC assessment and property tax records are important evidence of your lawful occupation, but they do not automatically guarantee entitlement to 645 sq. ft. in redevelopment. The developer cannot arbitrarily ignore BMC records without supporting legal or sanctioned documents.

You should issue a legal notice and have all relevant documents (assessment extracts, tax records, tenancy records, sanctioned plans, etc.) examined before accepting the proposed area. If required, you may approach the appropriate Court or Authority for appropriate relief.

Saurabh Agrawal

Considering the 1997 extract the area is 475 sq.ft

The additional 170 sq ft is shown in the 2007 -08 assessment 

As per DC regulations only the unit reflecting in the 1995-96 extract is to be considered for rehab 

That's why the builder claims that he has to give you only 405 (it should be 475 if the 95-96 extract showed area as 475)

In any event if the builder allots you 645 sq ft he will get 50% of that area as incentive fsi which he can sell in open market for profit 

So I don't understand why the builder is not supporting you 

Is the BMC survey done ? Is your name and carpet area and unit included in the Annexure 2 list of eligible tenants ? 

I need to see the papers 

This is a classic and very common conflict in Mumbai's redevelopment landscape. Developers routinely try to reduce a tenant’s certified area to cut down on their own rehabilitation liabilities and maximize their free-sale profit margin.

The developer cannot arbitrarily override BMC’s official records, but the exact area you can legally enforce depends strictly on how and when that "old tenant extension" was recorded.

Under Mumbai’s Development Control and Promotion Regulations (DCPR 2034), a certified Assessment Extract / Inspection Extract from the Municipal Corporation (MCGM/BMC) serves as primary, legally admissible evidence of a tenement's existence and size prior to the critical cut-off dates (such as June 13, 1996, for cessed buildings).

If the BMC has been collecting property tax and rent based on636.58 to 645 sq. ft.for decades, that area is recognized by the planning authority. The developer will use the exact same BMC records to claim a higher Floor Space Index (FSI) or incentive benefits from the corporation. Legally, they cannot use your large area to get extra building rights from the BMC and then turn around and tell you your flat is only 405 sq. ft.

The developer is a private entity; they do not have the statutory authority to determine what is legal or illegal space, only the BMC does. If the developer believes your structural layout does not match standard RERA carpet area definitions, they must raise this with the BMC during the verification and certification of the Certified List of Tenants (the Eligible Tenant List). They cannot simply hand you an agreement for 405 sq. ft. and force you to sign it.

You may immediately visit local BMC Ward Office (Assessment & Collection Department). Apply for certified, stamped copies of the 1997 and 2007-08 Assessment Extracts, alongside your lifetime property tax payment logs. Do not rely on loose photocopies. Then you may send a legal notice/written objection to both the Developer and the BMC’s High-Powered Committee / Assistant Municipal Commissioner. State clearly that you are an occupant of a 645 sq. ft. area as per official municipal records and will not consent to any redevelopment scheme that registers your area as less. Attach your certified extracts.

Never sign a Permanent Alternate Accommodation Agreement (PAAA) or a consent letter that explicitly states 405 sq. ft., even if the builder verbally promises to "make it up to you later." Once you sign a contract accepting a lower area.

If the BMC has assessed your property at ~640 sq. ft. and accepted your money for it for over 25 years, the principle of estoppel  applies. The corporation cannot easily claim the area is non-existent, and the builder cannot strip away your rights over regularized square footage.

If the developer threatens to stall the project or leave you out, remember that a redevelopment project on a BMC-acquired or cessed building cannot smoothly progress without resolving tenant eligibility disputes. If they refuse to budge, your recourse will be filing a Writ Petition in the Bombay High Court or approaching the MahaRERA authority (if the project is registered) to stall their permissions until your area is correctly factored in.