Simple, if the building is valued at 1.2B, you sell for 800M and pay the stamp duty of 4%.
The balance of 400M you do transfers to personal accounts held with various banks. Or you pay offshore.
Anyways no one is going to ask Judy or Jimmy why they received 100M to their account...
I have a friend who bought a house for 23M but paid 19M officially and the developer took 4M cash cash.
Business opportunities are like buses,there's always another one coming