A. Occupancy Certificate is very seminal document to establish your marketable title over apartment flat from the point of future deal.
B. When a residential apartment has been completed as per the norms approved building plan that concerned BBMP/BDA/BMRDA engineer will visit the spot and issue the completion certificate (CC) to the building subject to non deviation building. However, deviation up to 5% is permissible as per the BBMP bye laws subject to penalty.
C. You can visit the local authority office to get clear clarity towards this project and can raise query as to whether this project has been completed as per the building approved plan or not? and Is there any legal lacuna to issue OC to this project or not?, In addition to this, you can contact local registered engineer to inspect the project to get deviation clarity.
D. A Khatha is different from Occupancy Certificate. You could see many flats have got A-Khatha in the absence of Occupancy Certificate which means high rise building must get OC. Moreover, All OC flats are having A Khatha but all A-Khatah flats might not have Occupancy Certificate. When a property is converted for residential purpose and got building approved plan, NOCs from KSPCB, FIRE, AIRPORT, BSNAL, BESCOM AND BWSSB and paid betterment charges. tax payments and complied all the legal requirements will get A Khatha. However, the point is that the said project might complied all the legal requirement without following building norms as depicted in approved plan which means deviation more than 10%. Under this situation, OC will be rejected but A-Khatha will be provided. For your information, once the flat is sold out and get the registration for under construction property that you will get Khatha based on Sale Deed's document to pay tax payment.
E. When project is completed and most of the flat buyers already occupied the premises without obtain OC that seems to be something went wrong in the procedural aspects and you can presume that much deviation could be seen. Hence, you must get commitment clause from the land owner towards the OC without demanding any additional clause. Else the land owners will demand much money in future to provide OC.