Riley, page-87

Hi ShareBeers yes there are some major variable inputs which need to be considered as you point out:

With the iron ore price at these levels the projects profitability grows substantially and therefore so does the need to consider corporate tax.
Tax comes into play with profits approaching $66m.

• VMS has tax losses available to offset future profits totalling $66m as at 30 June 2020 ( see annual report 2020 page 54)

So in your last scenario: a simple calculation approach

Net profit after tax calculation could look like:

Net profit before tax $135m
less Tax losses available $66m
Taxable Income $69m
tax @ 26% =$18m.

Net profit after tax = $135m - $18m = $117m based on your assumptions.
cheers