Six months after Ms Trad handed down the budget, Queensland's projected debt is expected to rise by $1 billion over the next four years.

It's now forecast to balloon to $91.7 billion in the 2022-23 financial year, due to major investment in infrastructure and lower than expected revenue in coal royalties among other factors.

The government will still have an operating surplus this financial year of $151 million, which is down from the $189 million announced during the budget.

Ms Trad said a new $5 billion Future Fund will be invested to generate revenue to begin paying down the debt.

The fund is a combination of $2 billion of the government's current debt retirement plan and $3 billion from the Queensland bureaucrats' defined benefit super fund.

A new bill will be brought before parliament next year to ensure income earned from the fund can only be used to pay down state debt.

LNP Shadow Treasurer Tim Mander said the government's new fund was a "sham" and it should not be taking from workers' super.

The state's mid-year review showed Queensland's economy would grow slower than expected.

In the June budget Ms Trad announced a projected growth of three per cent but this was downsized by half a per cent.

Australian Associated Press