Most people don't realise it, but we're on the verge of letting foreign multinationals pay less tax on the profits they earn in Australia because we locals don't mind paying higher tax to make up the difference.
Our almost unique system of "imputing" to Australian shareholders the company tax already paid on their dividends means they have little to gain from Malcolm Turnbull's pressure on the Senate to phase the rate of company tax down from 30 per cent to 25 per cent, over about 10 years, at a cumulative cost to the budget of $65 billion.
So what can we hope to obtain in return for our generosity to foreign businesses? Economic theory (which may or may not prove realistic) assumes it would induce them to increase their investment in Australia which, in turn, would increase the demand for Australian workers relative to their supply, thus bidding up their price (otherwise known as wages).
Note that, contrary to all Turnbull's said about his "plan for jobs and growth", the theory does not promise a significant increase in employment – mainly because the theory assumes the economy is already at full employment before the company tax rate is cut.
As my colleague Peter Martin has written, Treasury's updating of its modelling of the theory finds that, after 10 to 20 years, consumer welfare (arising mainly from higher wages) would be $150 per person higher than it otherwise would be.
Doesn't seem a lot.
Apart from the initial benefits of the company tax cut going pretty much only to foreigners, another reason Treasury's modelling has always shown the ultimate benefits to us as being surprisingly small is Treasury's further assumption that the budgetary cost of the cut would have to be covered by some means.
Treasury's consultant modelled several possibilities: by cutting government spending (don't hold your breath), imposing a lump-sum tax (a textbook fav), increasing the goods and services tax, or by letting bracket creep quietly increase income tax (the most likely).
Trouble is, the model's assumption that increased taxes would harm the economy's performance diminishes the good the lower company tax is assumed to do. As Milton Friedman liked to say, there are no free lunches (you'll end up having to pay, one way or another).
So the impression the government and big business are trying to give us (and naive crossbench senators), that only an economic wrecker would oppose a lower company tax rate, is just spin.
As always, every possible economic policy change has costs as well as benefits, which should be debated. I think the case for cutting company tax is weak.
With the government taking such a propagandist line, the most dispassionate advice we've received has come from evidence Reserve Bank governor Dr Philip Lowe, and an assistant governor, Dr Luci Ellis, gave to a parliamentary committee last year.
Lowe pointed out something no other official has mentioned: the main countries are engaged in a bidding war, in which each moves to a lower company tax rate than the others, hoping to pick up a bigger share of the world's foreign investment - before some other country cuts to an even lower rate.
You can imagine how much the world's chief executives love this game and are urging their own government to put in the lowest, supposedly winning, bid.
But the longer everyone keeps playing, the closer we'll come to the point where no country has any company tax to speak of – and no country has any competitive advantage over the others. All we'll be left with is a distorted tax system.
Lowe's point was that we should think twice before we join this mutually destructive game. Why would a tax war be good, whereas a trade war would be terrible?
The proponents' latest argument is that, now the US is cutting its company tax rate to 21 per cent, we'll get little foreign investment if we don't cut our rate from 30 per cent.
What no one seems to have noticed is that the case for a company tax cut has now turned from positive to negative. It's not that we'll gain anything by cutting, but just that we'll avoid losing if we don't.
But you don't have to accept that argument if you don't want to. Behavioural economics reminds us that the proponents have "framed" our choices in a way that favours their case.
They want us to accept without thinking that foreign companies make their decisions about whether or not to invest in Oz solely by comparing the rate of our company tax with other countries' rates.
That is, foreigners take no account of how our special tax breaks compare with other countries' tax breaks, nor any non-tax factors that make investing in Oz attractive (say, we've got better iron ore than everyone else) nor even that they don't have to worry about our taxes because their lawyers know how to avoid paying them.
As Lowe and Ellis explained to the parliamentary committee, the notion that multinationals focus solely on the rate of our tax is highly implausible.
I think all those other factors mean we're unlikely to attract insufficient foreign investment, even though the US has cut to 21 per cent.
But Treasury's been a great worrier about us attracting enough foreign investment for as long as I've been in the game, without there ever being much sign of a problem.
So, what's eating Treasury? My theory is that it hasn't adjusted its thinking since we moved from a fixed to a floating exchange rate in 1983.
What the proponents of a lower company tax rate don't tell you is that, with a floating dollar (and all else remaining equal), the more successful we are in attracting foreign investment – as we were in the resources boom - the higher our exchange rate will be. Is that what we want?
