You need to verify a lot of documents to verify that the building is legal and has good title.
Documents to be verified:
1) Parent Deed / GPA : This is one of the most important document to trace the ownership of the land and flat. This document is is primarily to trace the ownership of the land where apartment complex is constructed.
2) Sale Agreement / Sale Deed: Sale Agreement and Sale Deed are two different things which is very often misunderstood by lot of buyers. Sale Agreement is a simple agreement between buyer and seller about the list of rules and regulations of the transactions. It is good idea to to carefully read the sale agreement before signing on it.
Sale Deed is totally different from the sale agreement.It is very important document for transferring the ownership of the property (land or apartment) from the seller. This document is registered with the sub-registrar office.
3) Khatha : If you sell/transfer your property, you should have Khatha for that property. Khata is an account of a person who has property in the city. Khatha is an account which reveals the details of a property like owner name, size of the property, tax paid, location of the property, etc. This is a most important legal document for finding the person who are liable to pay the tax for the property.
4) Encumbrance Certificate (EC): Encumbrance Certificate is an important evidence to prove that your property is not under any liability like outstanding loans.
5) Layout Plan:It is proof that the land was surveyed and builder or real estate person will made as layout with number of plots, park area, road, etc. and submit to the govt. authority for the approval. Govt. specifies set of rules that has to be satisfied to approve as a layout. If the submitted layout meets all the standards, then that layout will be register with the government.
6) Occupancy Certificate: Occupancy Certificate (OC) is issued by the BBMP/BMP authority to the builder after completion of the apartment.
If all the above documents can be verified in the originals you can proceed to buy. Get them verified by a lawyer locally.