I agree with you there...this tax can be devestating.
I look at this as a double tax computation...
1st they take 70% of everything over a certain amount (in your example $ 850) then..
2nd they take their normal tax on any profit ( they do allow you to take a credit for the windfall tax) but that is before they have figured if you are making any money at all..
To me this has just put all projects that do not have a real low production cost out of business as the only way these high cost companies make any money is if the price of gold rizes significantly...but if you have to give 70% of that price increase to the government you will never make any money
Example...
Lets say the base is $ 850 and gold goes to $ 1850 and it costs you 1400 an oz to produce the gold...
Your WPT per ounce would be $ 1000 x 70% = $ 700
Your regular tax per ounce would be
Revenue $ 1850
Less:
Expense -1400
Less WPT -700
Your loss would be 250 per ounce ......therefore no income tax but
Your cash flow is negative....( 1850-1400-700)
Obviously no one would do this but without the WPT you would make $ 450 per ounce !!
This is a far fetched example but it shows what could happen.
I hope all of my assumptions are wrong and what I have put up here is not what might happen....it is all my thoughts for the moment...I wish there was better information on how the calculations will be made but this is how I see it for now..
All IMHO