Federal independent MP Rob Oakeshott has been granted a briefing from Treasury to sort the "rhetoric" of the mining tax from the reality.
Mr Oakeshott has written to Prime Minister Julia Gillard and Treasurer Wayne Swan expressing concerns about the minerals resource rent tax (MRRT).
This followed the release of figures showing forward estimate receipts for all taxes, including the MRRT, down more than $20 billion since the May budget forecast.
"I remain concerned at the rhetoric of 'spreading the benefits of the boom' from the mining industry to other sectors, when the actual benefits to those sectors appear to be far outweighed by the difficulties associated with the record exchange rate," the NSW independent MP wrote.
Mr Oakeshott said allowing mining firms to deduct from their MRRT liability all state government royalties had the potential to minimise the tax companies pay.
He was concerned the MRRT receipts equated to a third, at best, of what was originally proposed under former prime minister Kevin Rudd's resource super profits tax.
"This has significantly compromised the scope for pursuing other tax reform, education and disability measures," Mr Oakeshott wrote.
He will also seek a status report on talks with the states on replacing the inefficient royalty system, which forms part of the Greiner report into the GST and state taxation being considered by the treasurer.
Mr Oakeshott, who is in Canada, told AAP on Thursday he understood a meeting was being arranged with Treasury.
There was a "range of options" he could take, depending on the advice from officials, but he would not specify whether they included motions or legislative amendments.