Builder

I am a builder and manufacturing a multi flat residential tower... I have contracted the labour job to C Ltd... Building material I am purchasing in my own name. I will get not get ITC for labour contractor bill... But will get ITC for building material... Now if I sell any flat before completion then I will charge 12%...and deposit the GST... what if I sell after completion... I won't charge any GST.. What will happen to ITC on Inputs taken by me... Will i get refund... Or credit shall lapse.... Any answers...