An analysis of the ACT budget pre- and post-reforms by former territory Treasury policy director Dr Khalid Ahmed has also found an almost $400 million boom in territory own-source tax revenue that is hitting Canberra's poorest households the hardest.

Dr Ahmed and economist Adrian Makeham-Kirchner, have completed a detailed analysis of the state of the territory's coffers to be presented at a public forum later this week.

The analysis asserts growth in the territory's own-source revenue base has outpaced economic growth since 2012-13, when the 20-year reforms began, and neither wages nor the territory's concessions system has kept pace.

Dr Ahmed claims the Chief Minister has broken his pledge that the reforms would be "revenue-neutral", and despite claims of a budget surplus this year, questionable accounting of renewable energy certificates also seemed to mask what was actually a $95 million underlying budget deficit.

The government did not publish an underlying budget operating position in the 2017-18 budget - a common measure used to determine whether a government forecasts a surplus or deficit in a given year.

When asked about the growing revenue lines at budget time, Mr Barr said he believed the government had not increased beyond population or economic growth, claiming the pledge still held true, though last year he also qualified the claims, saying reforms were now "broadly revenue-neutral in aggregate".

A Treasury spokeswoman disputed Dr Ahmed's claims on Tuesday, saying the government's figures estimated the percentage of own-source revenue to gross state product fell from 4 per cent to 3.8 per cent from 2008-09 to 2011-12, and rose only from 3.8 per cent to 4.4 per cent from 2012-13 to 2016-17. The government said that if that figure had held at 4 per cent for the 2012-13 to 2016-17 period, the government would have raised $41 million less a year than it actually did.

Mr Barr did not respond to requests for comment, instead referring all Dr Ahmed's claims to Treasury.

Dr Ahmed analysed the four years before reforms began and the four years after, showing the ACT government's own source tax revenue grew at 5.2 per cent a year from 2008-09 to 2011-12, but ramped up to an 8.2 per cent per annum growth rate from 2012-13 to 2016-17.

It also shows the growth in territory own-source taxation was on par with growth in the ACT's state final demand in the first four-year period, but tax revenue growth outpaced growth in state final demand in the second four-year period, at 8.2 per cent compared to state final demand growth of only 1.1 per cent a year.

Dr Ahmed said about one third of the territory's own-source tax revenue came from households, and the rising tax burden on Canberra households meant residents had less to spend on other essential needs.

He also said the way the government was accounting for revenue from large scale renewable energy certificates had misleadingly boosted the government's coffers by $34 million in 2017-18, and more in the out years, through shifting when revenue was recorded in the budget.

Dr Ahmed said the government's real underlying budget position was to be about $95 million in deficit in 2017-18, once the certificates were removed from the equation, as the certificates have no cash value and government policy was to surrender the certificates, not sell them on the market.

Another measure boosting the government's bottom line, he said, was the almost four-fold increase in government land sales dividends, of which he has previously been critical.

He said the government's total own-source tax revenue rose by almost $400 million in three years to 2017-18, and if the government had maintained the same revenue to gross state product as at 2011-12, it would have received about $332 million less in revenue.

Mr Makeham-Kirchner's analysis further examined the tax revenue in relation to economic dynamics and the specific households that were facing the brunt of rising taxes.

He said he found the vast majority of the increases were left to be met by households, rather than business, and the impact was disproportionately felt by the territory's 88,000-odd lowest income households.

Mr Makeham-Kirchner said those households were the 57 per cent of Canberra households below the ACT's relatively high average income, including the 37,000-odd the ACT Council of Social Service calculates are living below the poverty line.

"When we talk about the ACT having on average higher incomes, you could easily conclude they have the capacity, but if you look at the distribution of those incomes, it is not the reality for 57 per cent of Canberra households," he said.

"With the fixed portion of these taxes, rates and levies increasing, it means at the lower end of the income distribution it's consuming a higher proportion of the household budget, and the concessions have essentially gone backwards in real terms."

Mr Makeham-Kirchner said Canberra taxpayers were also feeling the stress from the rising taxes and fixed charges, shown through the latest ABS survey of household incomes, completed in 2015-16.

He said the survey showed a reduction in the number of households feeling no financial stress, and an increase in households feeling four or more sources of financial stress, particularly on being able to have dinner with friends or pay for things in a family emergency - issues he said contributed to a sense of community.

"Given what we saw in 2015-16, and the increased tax burden since then, you'd have to realistically conclude the stressors are only going to increase," Mr Makeham-Kirchner said.

Dr Ahmed said examining the full effects of the reform were important, as many other jurisdictions were closely watching the ACT's stamp duty reforms, but he questioned what the territory had to show for the changes.

He said that it now defied common sense to accept the government's claim the reforms had been revenue-neutral.