You can but the title will be legal for that illegal construction 

You can purchase the flat as said flat has been constructed  as per sanctioned plans 

only the additional floor is illegally constructed and can be demolished 

however if no OC is issued don’t purchase flat in said building 

If OC is not given builder cannot deliver possession of flat 

electricity and water connections should not be provided to illegal constructions.

SC has held that All the necessary service connections, such as, electricity, water supply and sewerage  connection shall be given by the service provider or board to the buildings only after the production of the completion/ occupation certificate. 

While it's possible to purchase a flat in a building on A khata land with a B khata construction, it's generally not recommended and comes with significant risks. 

However as the basic essential services  like electricity and water supply have been provided considering the status of the B khata construction, you can proceed if the builder has provided OC to the flat you intend to purchase.

However you may keep away from buying a flat in the floor which has been constructed by deviating the approved construction plan.

It's generally not advisable to buy a flat in Bangalore without a valid Occupancy Certificate (OC) or Completion Certificate (CC). 

These certificates are crucial legal documents that ensure the property is safe, built according to approved plans, and complies with local building regulations.

 Without them, you risk facing potential legal issues, difficulties in obtaining utility connections, and challenges in reselling the property. 

Dear Sir,

B Khata properties are technically unauthorized constructions.

You may face difficulty in getting home loans, OC, or future building regularization (unless Akrama-Sakrama is revived).

Avoid purchasing this flat unless:

• You are comfortable with the legal risks (no OC, deviation).

• You do not require bank financing.

• You are buying at a deeply discounted price.

• On 17 December 2024, the Supreme Court of India ruled that no essential services—such as electricity, water, or sewerage connections—and no loans may be provided to buildings without a valid Completion Certificate (CC) or Occupancy Certificate (OC). Banks and service providers must verify these documents before sanctioning any connections or loansou are prepared for potential litigation or regularization costs later.

• 
  Civil Appeal Nos. 14604–14605 of 2024 (Rajendra Kumar Barjatya & Others vs. U.P. Avas Evam Vikas Parishad & Ors.), delivered on 17 December 2024
  

Dear Sir/Madam,

You may purchase at your own risk and not approval by competent authority may be harmful in long run. 

Dear Client,
● Shall I go ahead with the purchase?
Going ahead with the purchase of the said flat is not recommended unless the
flat concerned is not the one constructed without permission. This is so
because, if so the flat would be at moderate to high legal risk due to the
deviation from the BBPM approved plans. Even if the property titles are clear
and the flat has an e aasthi certificate, the purchase of the flat may lead to
complications in the future.
Legal Principle: As per Section 321 of Karnataka Municipal Corporations
Act, 1976, if the commissioner is satisfied that the construction of any
building has been completed otherwise than in accordance with the plans or

particulars on which such permission or order was based, he may make a
provisional order requiring the owner of the building to demolish the work
done, or so much of it as, in the opinion of the Commissioner, has been
unlawfully executed, or make such alterations as may, in the opinion of the
Commissioner, be necessary to bring the work into conformity with the Act,
rules, bye-laws, directions or requisitions as aforesaid, or with the plans or
particulars on which such permission or orders was based and may also direct
that until the said order is complied with the owner or builder shall refrain
from proceeding with the building or well or hut.
However, the downside of purchasing the flat is that, many banks may be
reluctant to approve home loans or buildings not registered as A Khata or
those without OC/CC. Future buyers may also be discouraged from buying
the flat due to the fear of legal complications. Without occupancy certificate,
utilities like BESCOM, water supply etc, in the future.
● What are the recent judgments of the Hon’ble Supreme Court regarding
buildings without OC and CC?
In Rajendra Kumar Barjatya and Anr. Vs. U. P. Avas Evam Vikas Parishad &
Ors. the Supreme Court has inter alia directed that all the necessary service
connections, such as, Electricity, water supply, sewerage connection, etc.,
shall be given by the service provider / Board to the buildings only after the
production of the completion/occupation certificate.
In conclusion, proceeding with the purchase of the flat is inadvisable.
I hope this answer helps. In case of future queries, please feel free to contact
us. Thank you.