The total cost is about 250 million US dollars, Nolan's largest budget.
Filming is taking place now, June 2019, in Tallinn, Estonia.
The word "TENET", chosen for the title, can be read in both directions. This will be related to the main character.
The definition of the title, "Tenet": "a principle or belief, especially one of the main principles of a religion or philosophy."
I've guess that the name "TANAT" is not just randomly chosen. It can be read in both directions, it will be some kind related to the mater of the main character.