The optimum retirement age under the now-closed Commonwealth superannuation scheme is 54 years and 11 months. If you leave it until 55 or older you lose the equivalent of 12 to 18 months of after-tax salary, Deloitte director Chris Richardson said. Put another way, if you retire at 56 and a half, you've worked the last 18 months for nothing.

And for people who decide to retire in the hope of a second career in the private sector, 55 is precisely the wrong age to look for a new job.

Mr Richardson made the comments in Deloitte's latest business outlook, published on Monday, where he also said the federal government's resistance to major stimulus spending right now might not be a bad thing, leaving some room to move in the event of global recession.

He said Canberra had the country's highest family incomes for two reasons - Canberrans were better educated and skilled than average, and they participated in the workforce in higher rates. But while the rest of Australia was improving workforce participation, that wasn't happening in Canberra.

The participation rate had been eight percentage points higher than the rest of the nation in the mid 2000s. Now, it was just three points higher.

"While a bit of that slide is because relatively more Australians are choosing to grow old in the nation's capital than was formerly the case, the bulk of it is because of stupidity," he said.

The quirk that Mr Richardson refers to applies to the generous Commonwealth Superannuation Scheme that was closed to new members in 1990.

The public service itself has produced two decades of inter-generational reports, highlighting the importance of keeping older people and women in the workforce for the health of the economy. Nationally, the message has got through.

"One of the stand-out successes of the Australian economy of recent years is that people are working for longer," he said. "But by and large that's not happening in Canberra. And the rest of the country is stealing an economic march on us."

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But there was no easy fix, since the problem was baked into rules that were next to impossible to fix and had been incorporated into the plans of many people.

The Deloitte business outlook said Canberra's population growth was strong, the ACT government was spending, and the university sector was solid.

But muted growth in the Commonwealth public service was keeping jobs growth sluggish, and wage growth looked likely to remain low for some time.

The economy was also held back by slowing home building, with housing construction set to play a lesser role in Canberra's economic growth and risks around the number of apartments being built.

Engineering construction was taking a breather with the end of stage 1 of light rail, but more than $500,000 was budgeted for capital works in the next four years, including stage 2.

"The ACT Government will plough ahead with existing plans for stage 2 despite a lack of Commonwealth endorsement (as well as a lack of a clear set of net benefits for this approach instead of, say, beefing up the existing bus network).

"Protracted negotiations with the National Capital Authority and technical issues on how to get light rail across the lake have already pushed back dates, with further delays raising the risk that Canberra's rail workforce hightails to Sydney and Melbourne - where there's no shortage of similar work."

Nationally, the Reserve Bank has been urging more infrastructure spending to boost employment and lift wages, but the federal government has resisted major stimulus spending.

Mr Richardson said he was "comfortable with current policy settings", even if the Reserve Bank cut the official cash rate as low as 25 basis points.

If the Commonwealth moved to stimulus on top of record interest rate cuts already made by the central bank, both would have spent their rainy day fund and have less room to move in a crisis, he said.

Risks were multiplying, "leaving the global geopolitical landscape liberally littered with tripwires", including the China-United States trade war, Brexit, the Hong Kong protests, Iran and the Saudis, and Kashmir.

Mr Richardson said uncertainty was creating the risk of global recession.

"Countless companies (as well as many families) simply don't know what the world's leaders will do next. Given that uncertainty, many are choosing to do nothing ... which means that major investments are being put on hold."