Rachel Reeves is being urged to use next week’s budget to ringfence health spending on prevention so it is protected from cuts when money is tight.

A letter sent to the chancellor by a leading health charity, thinktanks and the body that represents accountants says carving out a new category of preventive spending would mean a healthier population and save the NHS money.

The letter, seen by the Guardian, welcomes Labour’s emphasis on prevention but says there has been a long history of previous administrations making similar pledges only for services that affect health outcomes to become a casualty of pressures on day-to-day budgets and a victim of short-term thinking.

Analysis by the Health Foundation – one of the signatories to the letter – showed that in the five years leading up to the pandemic (2014-19) spending on hospitals rose by 10%. The share of health spending devoted to prevention fell by 10% during that period.

Anita Charlesworth, the Health Foundation’s chief economist, said there needed to be a shift “so we are spending more on prevention and less of failure”.

Charlesworth said that a report by the independent Office for Budget Responsibility on the fiscal risks facing the UK had found that extra spending on prevention would lead to increased spending on the state pension but higher tax revenues, lower spending on welfare and less pressure on the NHS budget.

“A healthier population would be really beneficial to the public finances,” she said.

The letter, also signed by the thinktank Demos, the Institute for Government and the accountants’ body Cipfa, says public policy “is littered with examples of prevention spending being cut to provide short-term funding to patch up frontline services, and there is too little incentive to invest in services that deliver long-term benefits”.

It cites evidence from the record of the Conservative governments after 2010, which cut spending on youth services and the Sure Start scheme for families with children under five despite evidence that they were having good long-term effects. Research by the IfG found that local authority spending on these services was cut by more than three-quarters between 2009 and 2023, while spending on looked-after children and safeguarding services rose by more than half over the same period.

“Current fiscal frameworks do not distinguish between spending on acute services and prevention, despite the evidence that investment in prevention can deliver a greater long-term return,” the letter says.

“Given the significant pressures on the public finances, the risk is that prevention spending will continue to be squeezed out in favour of meeting short term needs, undermining the government’s commitment to taking a long-term, prevention-led approach to improving public services.”

Reeves has made clear that she intends to change the rules governing the public finances to allow her to borrow more to invest in capital projects, a move designed to deliver stronger growth.

All Whitehall ministries are given departmental expenditure limits by the Treasury, but the letter calls for a new category of spending – preventive departmental expenditure limits – in which prevention would sit alongside day-to-day spending and capital investment, enabling the government to identify and track spending.

“Strengthening the fiscal framework would enable the Treasury to better hold government departments to account for long term investment in prevention, and support mission-driven government by ensuring that this money is used to transform services”, the letter says. “Without this, we fear the government’s good intentions to promote prevention may once again fall by the wayside.”

A Department of Health and Social Care spokesperson said: “Our 10-year health plan will reform the NHS by shifting its focus from sickness to prevention.

“We’re introducing measures to ban junk food adverts targeted at children, as well as new NHS health checks to catch health problems earlier and prevent them worsening.

“Our tobacco and vapes bill will stop future generations from becoming hooked on nicotine and finally make Britain smoke-free.”