By David Deans & Daniel Davies
BBC Wales
The NHS and council services like schools and transport will be spared when the Welsh government sets out plans to balance its books later.
Other Welsh government-funded services could face cuts in the announcement.
Inflation has been blamed for the unusual exercise, which has come in the middle of the financial year.
Welsh Tories have criticised spending on “vanity projects”, while Plaid Cymru questioned how transparent the process has been.
The Welsh government said it was “under unprecedented pressure caused by the impact of inflation, more than a decade of austerity on public services, and the UK government’s mismanagement of the economy”.
Finance Minister Rebecca Evans will announce more detail in the Senedd on Tuesday afternoon.
A spokesperson said she would announced a “package of financial measures which protect Wales’ public services, NHS and transport” – she has previously committed to protecting council budgets.
First Minister Mark Drakeford had asked his ministers to find savings during the summer, describing a shortfall of £900m.
How will the cuts affect me?
Ms Evans has kept this announcement under wraps, but warned recently when cuts happen vulnerable people “inevitably” feel the effect.
Even though he has asked every part of the government to cough up, Mr Drakeford said the whole point of the exercise was to protect the NHS.
Councils have been told the main pot of money they get will not be raided. That funding pays for schools, social services, rubbish collections and a host of other services.
If the health service, councils and Transport for Wales – which funds rail services – are relatively safe, the burden falls more heavily on other departments.
Which yet, we do not know.
But that could mean further education, climate change, culture and sport, rural affairs and other environment services take a hit.
And if there are cuts, that can mean fewer services available to the public.
Why is this happening?
Even though public spending is rising, costs are rising faster.
Inflation is eating into the Welsh government’s budget, meaning it gets less for its money.
The same is happening to household budgets, so the Welsh government has had to dig deep to fund pay rises for public sector workers.
The cost of medicines and energy has shot up for a health service grappling with massive waiting lists.
Fewer passengers than expected are travelling to work on the railways compared with before the pandemic.
The Welsh government has to make up the shortfall in lost ticket sales, thought to be £30m less than expected this year.
A senior Welsh government minister said the process to find savings mid-year was “highly unusual” – with the Welsh government typically setting its budget for the next financial year over the winter.
There have been questions over whether the Welsh government could have taken action earlier.
Dr Larissa Peixoto Gomes of Cardiff University told the BBC’s Politics Wales programme her team had “mentioned the possibility of this shortfall” in 2022 with a forecast of £800m.
“The Welsh government seems to have been shocked when this actually happened,” she said. “It was predictable.”
What does the Welsh government pay for?
Any service that is devolved to the Senedd is funded from the Welsh government’s budget of about £20bn.
The health service takes the biggest chunk of that.
Another big portion is funnelled through councils, who are responsible for running schools and providing care to the elderly.
Mark Drakeford has created a big climate change department in his government, responsible for transport and house building, among other things.
But the Welsh government is not responsible for benefits and the police – those things are funded in Westminster.
What does the opposition say?
Plaid Cymru has accused the Welsh government of “leaving people in the dark”.
The party has said it is unclear how much is actually going to be saved, after the finance minister suggested £900m might not be the figure they are dealing with.
Peredur Owen Griffiths of Plaid said the process has been frustrating: “It’s been a long time coming and a lot of anxiety, a lot of pressure on public services out there that don’t really know what’s what’s going to happen next.”
Meanwhile the Welsh Conservatives want the health budget ring-fenced and have criticised spending on “vanity projects” like the 20mph speed limit switch, and Senedd reform.
The Welsh Conservatives’ Peter Fox said ministers “could have pre-empted what was likely to be happening.”
Conservatives in the UK government repeatedly describe the amount of cash it is giving the Welsh government as a “record” settlement.
When will we find out?
Rebecca Evans will make a statement on the floor of the Welsh Parliament mid-afternoon on Tuesday.
As it stands we do not know how specific the announcement will be.
That would mean we may not be able to spell out exactly which part of Wales’ public services will be worse off.
What happens next?
This is not the end of the story. Another budget is being drawn up.
Ms Evans will be back with plans in December for what the Welsh government will spend in the next financial year, which begins in April 2024.
The same pressures will likely remain – with prices going up, in the health service and in public transport.