The Institute for Fiscal Studies (IFS) has warned tough choices are "unavoidable" as the government prepares to finalise its spending plans across a range of sectors.
The government says its spending review on June 11 will "scrutinise every single pound the government spends".
Ahead of the review, the think tank IFS has indicated the level of spending on the NHS will dictate whether or not cuts are made to areas deemed "unprotected" outside of health, defence and education.
The BBC reports Whitehall insiders suggest the cuts will be "ugly" with ministers desperately fighting too win even small amounts of money for their departments.
The IFS has said that while funding for transport, net zero, hospitals, schools and prisons rose in 2024, year-on-year inreases were to cease due to the government's other commitments.
Chancellor Rachel Reeves has ruled out borrowing more money and her decision not to further increase taxes has led to expectations from many that spending cuts will have to be made.