Queensland is forecast to record back-to-back deficits over the next two years, in what the state government says is a deliberate move to support those struggling with the cost of living.

The upcoming state budget will detail an expected $3 billion deficit for the 2024-25 financial year, before reducing to a deficit of less than $1 billion the following year.

It's a stark difference from the $122 million surplus previously forecasted, followed by an expected $91 million surplus the following year.

Queensland Treasurer Cameron Dick blames record spending on health and housing as reasons for the deficit, along with yet-to-be-announced cost-of-living relief.

He stressed the figures were subject to change.

"These are deliberate choices that all political parties must make, whether to prioritise people or numbers on a balance sheet."

Shadow Treasurer David Janetzki told the House the government was "more concerned with how things look, rather than how things actually are". 

"Never has a Queensland Government spent more, borrowed more, or taxed more and left Queenslanders with less to show for it," he said.

But economists say the forecasted deficit could be due to three reasons.

Conservative coal assumptions

Independent economist Saul Eslake says governments often make conservative assumptions about coal prices.

"Effectively the government is taking out insurance in spending money it doesn't have," he said.

Coal prices rose substantially in the aftermath of Russian President Vladimir Putin's invasion of Ukraine when production was predicted to be impacted from sanctions imposed by Western governments.

"Coal prices are still somewhat higher than the lead up to the invasion," Mr Eslake said.

"That means that Queensland is generating more revenue in mining royalties than what was expected."

But Mr Eslake says that with the combination of China's slowing economy and the world looking towards renewable energy there is the expectation that global coal prices will fall.

"Therefore governments who are dependent on commodity revenue these days err on the side of caution," he said.

Coal royalties generated an additional $8.6 billion in revenue for Queensland in this and last financial year.

That's expected to moderate significantly to an average of $280 million per annum in the three years to the 2026-27 financial year.

Revisions of GST revenue

The second factor in influencing the deficit according to economists would be the state's share in GST revenue, which has been advised down.

According to the Commonwealth Grants Commission, which provides annual revisions, Queensland's GST distributions are estimated to fall for 2024-25.

This is due to an increase in Queensland's relative revenue raising capacity.

"In recent years the state's revenue has been substantially enhanced by the high level of coal prices from the invasion of Ukraine," said Mr Eslake.

"So Queensland, like New South Wales, might be getting less revenue from GST for the next few years".

Cost-of-living spending

The final influencing factor, economists say, will likely be due to the Queensland government's cost-of-living relief package.