Mr Barr on budget day in June said the territory was headed for a $43 million surplus.

But final financial statements for 2018-19 reveal there was a $161 million negative turnaround on the predicted surplus, partly attributed to light rail stage one.

The financial statements said there had been higher than anticipated operating costs for the project related to underground utilities diversions. It also said landscaping, demolition and planning of other projects cost more than planned.

These combined costs accounted for about $110 million extra in expenses than forecast in the June budget.

It also blamed poor property market conditions for a more than $100 million shortfall in expected revenue from contributed assets.

The statements showed actual revenue for the financial year was about $63 million lower than predicted in the June budget, while expenses were up more than $100 million.

A spokeswoman for Mr Barr said the deficit would not negatively impact future years' bottom lines.

She said the higher capital works costs - like those associated with light rail - were set to be depreciated over several decades but were instead put as an expense in a single year.

Asked whether Mr Barr still planned for a surplus by 2021-22, the spokeswoman said the 2019-20 budget review would be delivered early next year.

"The ACT budget will be subject to the same impacts as other state budgets - the Commonwealth budget, declining GST revenue due to weak consumer confidence, variability in the housing market and a weak national economy," she said.

Despite the shortfall, the government's actual tax revenue was about $36 million higher than what was predicted in the June budget papers. Commonwealth grants also contributed about $20 million more than predicted.

When compared with the actual tax revenue from 2017-18, the government increased increased its tax revenue by 13 per cent.

Mr Barr's eighth budget, delivered in June, was expected to deliver a $43 million surplus in 2018-19, before an $89 million deficit this fiscal year.

It forecast a second year in deficit in 2020-21, at $66 million, before a $135 million surplus in 2021-22, followed by a big rise to an estimated $413 million surplus in 2022-23.

Some commentators have already expressed skepticism the government will be able to return to surplus as planned.

Former executive director of policy at ACT Treasury Khalid Ahmed has said Mr Barr's forward estimates and the projected revenue jump would be "miraculous" if achieved.

"The figures are not credible, that growth in revenue is not sustainable," he said in June.

He said it appeared unlikely the budget would return to surplus in 2021, as predicted by government, especially to the extent it has projected in forward estimates.

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Opposition leader Alistair Coe said last year's budget deficit came despite record revenue.

"Canberrans should be very concerned about further increases to rates and taxes under ACT Labor," he said.

The financial statements also confirmed debt jumped by almost $1 billion last fiscal year.

Net debt sat at $2.216 billion at the end of the financial year. This was $913.6 million higher than 2017-18.

Mr Barr said this was mainly a result of higher borrowing to fund infrastructure initiatives and the recognition of lease liabilities for public private partnerships.

Net worth sat at $14 billion.

When he handed down his budget in June, Mr Barr spoke at length about a "significant" gulf in Commonwealth infrastructure spending in Canberra.

A consultant's report, commissioned by an ACT Parliamentary committee, later criticised the budget for being "shrill" and too political.

It said the political commentary in the 2019-20 territory budget was unbecoming for a small jurisdiction that wanted to be taken seriously.