The contribution to federal tax revenue from multinational oil and gas companies has slumped, and a senior academic has warned that the huge gas projects coming online off the West Australian coast will not contribute a single dollar in royalty payments in her lifetime.
The dire forecast for what little the next stage of the mining boom will deliver calls into question claims by Malcolm Turnbull and Bill Shorten that their parties are committed to cracking down on multinational tax avoidance. 
The only royalty-like payment applicable to liquefied natural gas projects in Commonwealth waters, including the $US70 billion ($95 billion) Gorgon plant operated by Chevron, is the petroleum resource rent tax. Despite the $200 billion invested in LNG in the past decade, there is little or no sign of any benefit to the nation via the PRRT. In fact, PRRT revenue is the only class of Commonwealth tax revenue that has fallen over the past decade.
In 2005, Canberra collected $1.9 million in PRRT. Last year, despite the explosion in LNG projects, revenue fell to $1.4 billion, and the 2016 budget slashed the projected take by almost half to just $800 million a year to 2020.
In   April, Fairfax Media revealed documents prepared for the West Australian Treasury that warned the Commonwealth would wait "decades" to receive any significant revenue from projects such as Chevron's Gorgon and Wheatstone and Woodside's Pluto gas field.
Diane Kraal, a Monash University expert in resource taxation, believes the PRRT system is a failure because it was designed in the Hawke-government era to tap super-profits from oil. PRRT is a profits-based tax that taxes "rents" - or excessive returns - above a specified rate after deductible expenditure, including exploration and capital investments.
While oil prices spike intermittently, Dr Kraal said, LNG supply is based on long-term contracts and profits will remain steady rather than super. "I doubt in my lifetime that those companies will be paying PRRT on gas," she said. "In effect, we are giving it away."
Dr Kraal, who has written a paper urging a review of the PRRT, has warned a senior Treasury official that the system is a white elephant, to the detriment of royalties, which are supposed to reflect that a nation's finite resources can only be extracted once and should therefore enrich the country as well as companies willing to invest in Australia.
At a Senate estimates hearing in   May, Roger Brake, the acting deputy secretary of Treasury's revenue group, was asked to explain the dive in projected PRRT.
He put it down to the lower Australian dollar, oil prices and the volatility of rent-based taxes. He warned that companies that invested in LNG are allowed to write off their investments against tax before being forced to pay royalties. Chevron, for example, has potential tax credits of more than $US67 billion.
"These projects can take a long time before they start paying PRRT, so you can get these long lags between when they enter production and when they start paying PRRT," Mr Brake said.
But sources have told Fairfax Media that the Australian Taxation Office is concerned that the PRRT will not deliver anything over time.
Treasury and the ATO declined to comment, citing election caretaker conventions. In its marketing material, Chevron pledged "direct taxation and royalty payments" of $1 billion a year by 2019, rising to $3 billion by 2024 and out to 2036.