His budget is down by about $10 billion a year as far as the eye can see. Our income from iron ore is down, and low wage growth means more of us are claiming family payments and other government benefits. For now he says he won't be raising taxes or cutting spending, on us. It would weaken the economy further.

But he sees spending on foreign aid as fair game. The Australian Council for International Development says our spending on overseas aid will fall from 0.32 per cent of national income to 0.21 per cent, the lowest level since records began in 1954 – when the Queen first visited Australia.

The Treasury projections say the economy will improve and the deficit will shrink without the government needing to do anything more than limit spending growth to its target of inflation plus 1 per cent a year.

But the projections aren't forecasts. The Treasury points out that its methodology automatically assumes the unemployment rate will return to 5 per cent during the next seven years. It assumes economic growth will accelerate by enough to make this happen and then drop back to its long-run average. It's an assumption not a forecast.

The budget would be back in surplus by the end of the decade on that basis, at the start of the Coalition's third term in office. It's a far cry from Joe Hockey's pledge after Labor's 2012 budget that, "based on the numbers presented last Tuesday night we will achieve a surplus in our first year in office and we will achieve a surplus for every year of our first term".

Like Wayne Swan before him, Joe Hockey is likely to leave the Treasurer's office without having delivered a surplus. But more-important things are at stake. Like all treasurers he is determined not to be one who pushes the economy into recession. That's why he'll let the deficit blow out by $10 billion a year for now and pick up the pieces later.

He is waiting for a real pick-up in the economy rather than a Treasury assumption.

Peter Martin is economics editor of The Age.

Twitter: @1petermartin