Redevelopment

Respected sirs,

we are the tenants of the chawl in mumbai having ground floor with mazzanine floor (not paying assessment tax),  we are going for redevelopment and the developer offers us 300 carpet area, the developer saying that you are not eligible for any compensatory FSI for not paying Assessment Tax, that is iiegal construction,

so please give me suggetion for the same and please tell me that any govt. resolution has passed or not.

 thank you,