While Treasury secretary Martin Parkinson’s warnings about the sustainability of our tax base are timely, they only tell half the story — or two-thirds, if we’re being generous.

At the same time as Parkinson, with the blessing of the Treasurer, is flagging the need to consider how Australians should pay more tax, and preferably more indirect taxes, the government is trying to dump two significant revenue sources, the mining tax and the carbon price, and has dumped two other revenue measures put in place by Labor last year — the closure of the fringe benefits tax rort on novated leases, and the (modest) tax on superannuation earnings over $100,000 a year. That’s the best part of $10 billion to $15 billion a year in foregone revenue, to the benefit of companies and high-income earners.

So it’s OK for the rest of us to pay more for everyday goods and services, but don’t dare touch mining super-profits, try to discourage carbon emissions or modify our absurdly generous superannuation taxation arrangements.

Fair enough that Parkinson — graciously given a stay of execution by Prime Minist Tony Abbott until after the G20 — wouldn’t bag the policy of the current government. He did, however, single out the Howard government’s 2001 decision to abandon indexation of fuel excise. That decision was Canberra at its worst: a minor administrative error by the Department of Transport, an act of “pure bastardry”, as one senior bureaucrat put it, by the Audit Office, and a terrified government facing electoral oblivion combined to inflict a substantial and growing hole in revenues that costs us billions every year.

Unsaid, but implied by Parkinson, was another criticism of the Howard government: its decision to give in to the demands of senator Meg Lees and the Democrats and allow exemptions to the GST based on nanny state notions like encouraging fresh food consumption. That exemption now costs state governments around $6 billion a year — $6 billion a year that could be used for paying for better services, higher-quality teachers, more public transport, more hospital beds. The exemptions for education and health cost another $7 billion or thereabouts.

That’s partly because: guess which areas of consumer expenditure have recorded the strongest growth in recent years? Health, education and food. There’s a reason why food programs like My Kitchen Rules and MasterChef now dominate the ratings.

“The GST exemptions aren’t even our biggest ‘tax expenditures’.”

On the other hand, at least the Howard government successfully implemented a major new tax in the face of political opposition, something Labor didn’t achieve while in government under Julia Gillard or Kevin Rudd — the carbon price was implemented despite an explicit promise not to do so in 2010, and the mining tax was badly botched and led to the knifing of Rudd.

The GST exemptions aren’t even our biggest “tax expenditures”. They’re not even close. The capital gains tax exemption on the family home and the concessional tax treatment of superannuation earnings and contributions have that honour; Treasury estimates superannuation concessions lead to nearly $28 billion a year in lost revenue. No one will ever touch the family home exemption, and we do want to encourage retirement saving via tax incentives, but they all point to the extent to which the debate about fiscal sustainability should start with the revenue that we’re not collecting under existing taxes, rather than lifting the rates of those taxes or introducing new ones.

Let’s not forget dividend imputation, either — more than $20 billion by some estimates a few years ago — which benefits shareholders, most of whom are superannuation funds. Ending imputation could finance a big drop in company tax without needing the traditional offset proposed by business of a rise in the GST.

While Parkinson is talking about our fiscal future, what he’s really painting a picture of is the past — and in particular the 1970s and early 1980s, when governments kept increasing spending beyond revenue and our tax system encouraged rorting like fringe benefits and the bottom-of-the-harbour scheme. It took a brave government to overhaul that tax system throughout the 1980s. Is the Abbott government similarly brave?

If its response is a higher GST while it slashes taxes for mining companies and high-income superannuants (the biggest current tax rort, albeit entirely legal), then the answer is “no” — especially when the government is engaged in partisan silliness like the Reserve Bank handout, running hugely expensive royal commissions aimed purely at damaging Labor and the unions and treating the sale proceeds of Medicare Private as a pork barrel to fund an “infrastructure hole” that simply isn’t there, rather than paying off debt or handing it to the Future Fund.