please help in below mentioned situation: apartment was booked before GST implimentation and partial payment was made with service tax and VAT, on balance amount GST is applicable. our flat value is as per agreement of sale of undivided share of land and agreement of construction together comes as X+Y. sale deed will also contain only this value (X+Y). The documents submitted for bank loan by builder to bank also mentioned X+Y as total flat cost. On top of this cost builder is collecting some other charges which he is terming as statutory deposits and other charges say Z, and he is collecting 12% GST on X+Y+Z. Statutory deposits are for BWSSB, BESCOM etc. My doubt is, whether he should compute GST on X+Y or on X+Y+Z. Please clarify.