Of course the changes to the rules for superannuation (and tobacco) aren't retrospective in the ordinary use of the term. No-one's being asked to pay extra tax on previous earnings. They're prospective. They apply from July 2017.

The Coalition outlined changes to superannuation in its pre-election budget.

From then, only the first $1.6 million of each retiree's accounts will escape tax. Earnings on the rest will be taxed at 15 per cent. It's a tax change, along the lines of the temporary deficit reduction levy and the budget decision about when the 37 per cent rate cuts in.

Come to think of it, the Howard government's decision to make super payouts tax-free for retirees over 60 would have been "retrospective" in the eyes of the industry. It changed the rules after the game started (in a way about which the industry didn't complain). Of course it didn't really reach back into the past, it only changed the rules from then on.

Nowhere is the prospective nature of the budget changes clearer than in the way the Institute of Public Affairs describes the new $500,000 lifetime cap for extra post-tax contributions (lifetime is defined beginning on July 1, 2007 when accurate records began).