Xstrata, Fortescue Metals won't pay resources tax

BHP Billiton and Rio Tinto will be the only two mining companies paying the new resources tax when the first sum becomes due on Monday and only because they helped design the regime.

The Australian reported Xstrata would not make a payment despite helping to re-jig the tax after Kevin Rudd was ousted as prime minister in 2010.

Fortescue Metals is not expected to pay anything for the Mineral Resources Rent Tax just yet, despite having launched a High Court challenge on whether the tax was constitutionally valid.

The payments will be based on the companies' estimates of their full-year liability, which will be significantly less than the gross amount of more than $5 billion assumed in the May budget.

Company sources told The Australian that could have been calculated at zero, or even yielding a net credit, but the two resource giants felt inclined to make some payment since they had such a large role in brokering the deal over the tax.