Queensland Treasurer David Janetzki says he has been warned by Treasury there is a "growing risk" the state's AA+ credit rating will be downgraded.

A lower rating would lead to higher borrowing costs for state projects ahead of the 2032 Brisbane Olympics. 

"There is structural deficits built into the budget, there is a growing risk of a credit rating downgrade — that is the Treasury advice," Mr Janetzki told ABC Radio Brisbane.

"The debt to revenue ratio ... is performing worryingly in Queensland." 

The credit rating is a measure of the state's expected willingness and capacity to repay any debt on time.

It is determined by reviewing the state's economic structure and prospects, financial performance, balance sheet position, liquidity and debt management strategy and the government's fiscal strategy.

S&P Global Ratings analyst Anthony Walker said any additional spending, whether on new policies or cost blowouts, "could weaken Queensland's budget and increase debt beyond our expectations".

"This could pressure our AA+ credit rating on Queensland, especially if additional spending is not offset by savings or revenue increases," he said.

What does it mean for Queenslanders?

Queensland's debt path is on track to reach almost $172 billion in 2027-28, with interest repayments of more than $7.7 billion, according to Mr Janetzki.

Queensland's credit rating has been AA+ since February 2009, when it was downgraded one notch from S&P's top rating of AAA.

Mr Janetski said his first official meeting after the LNP took government was with global ratings agency S&P, which had warned during the October election campaign that the state's AA+ credit rating was at risk of being downgraded.

Former treasurer Cameron Dick said a credit downgrade would be "a tax on all Queenslanders", as it would mean higher borrowing costs, resulting in "less infrastructure and fewer services".

He said the state's credit rating was deemed "stable" by S&P in September.

"Credit ratings don't get up one day and decide to downgrade a state, that's not how it works," he said.

"The first step is to put a state on a negative outlook, that's the first thing that happens before a downgrade might happen, and that didn't happen."

What's the government doing about it?

In its latest research on Queensland, S&P said containing operating expenses and achieving saving targets would be "very important" to the state maintaining its credit rating.

It said total operating expenses in the 2024 financial year are almost 40 per cent higher than three years ago.

Mr Janetzki told an Australian British Chamber of Commerce event today that Treasury had warned the state has a "significant and growing debt burden that won't stabilise", and "a concerning increase in the interest burden likely to exceed critical thresholds".

He said the government would continue to "calmly and methodically" go through the budget.

"I said before the election I wanted to return a mature and calm discussion to what drives our prosperity and underpins our budget," he said.

Mr Janetzki said the increased costs of projects the LNP had inherited from the former Labor government was contributing to the heightened risk of the state's credit rating being downgraded.

"It is now highly likely that Queensland will be left and we will inherit an outlook downgrade, and ultimately a rating downgrade," he said.

"It is time for us now to continue that work on identifying the project overruns and cost blowouts so we can get a clear picture."

Higher interest on global borrowing

Griffith University professor of finance Dr Robert Bianchi said a credit rating downgrade would increase the interest rate the Queensland government would need to pay for any debt it borrows from global financial markets.

"Victoria is already at that AA rating and there's an eight-basis point difference," he said

"So on a 10-year bond, if we grab all of Queensland's debt and we converted it all into a giant 10-year bond that's an additional $78 million per year of additional interest that we would have to pay."