With a target on his back, Barr has a budget hiccup to explain

The deficit in the ACT budget is bigger than it was supposed to be. Not by a rounding error, either. Try $340 million.

Mr Barr's economic management rightly attracts a lot of attention. He's been pulling the purse strings for more than a decade now and is the country's current longest-serving treasurer. The Liberals were not backward in coming forward to make their displeasure known when the AAA credit rating was downgraded last year.

With an election on the horizon, the ACT's mid-year budget update hands the opposition a splendid political gift. They can - and no doubt will - spin the bigger deficit as a broken economic promise.

The reality is a little more complex. The larger-than-forecast deficit is a result of lower revenue. The goods and services tax, which is collected and distributed by the Commonwealth, is lower. Consumers are, unsurprisingly in times of steep inflation, spending less. Did someone say "cozzie livs"?

Payroll tax revenue has dropped, too.

The crackdown on contractors in the Commonwealth public service has come with a price. It was a part of the federal Labor pitch that resonated in this city, just as long as you weren't one of the people back in the department collecting both your defined-benefits pension and a tidy contract.

Now the ACT's budget is feeling the sting because there are fewer people working in the private sector, reducing the payroll tax take. Payroll tax revenue will be $59 million lower than expected, the mid-year budget revealed.

Economics is so often a battle waged with double-edged swords. Just look at this payroll tax dilemma.

Mr Barr acknowledged the budget challenges were not unique to governments. Households had faced tough times, too.

"The government made a decision not to burden households any further with any tax increases through the budget review ... what we'll be focusing on is ensuring that we deliver our remaining election commitments," he said.

The ACT is not in complete control of its own fiscal destiny. Pay some attention to the federal government behind the curtain. The variance from ACT budget to budget shows as much.

Mr Barr will face the tricky job of explaining this reality. Getting past the peak of inflation, which Mr Barr believes Canberrans have, and the "fairer" version of the stage three tax cuts that will put more money in more pockets from the middle of the year will help his cause.

The Chief Minister's success in October depends on his ability to convince Canberrans to stay the course on his longer-term vision, no matter what he would see as short-term budget deficit hiccups.