Macmillan Cancer Support, one of Britain’s biggest and best known charities, is planning to axe 150 jobs – one in 14 of its workforce – saying that it is getting harder to raise money to cover rising demand for its help due to increasing numbers of people living with cancer.

The charity, whose services play a vital role in local NHS provision, spends £250m a year funding about 11,000 specialist cancer nurses and care workers and providing financial, practical and emotional support and advice to the public, including thousands of £200 grants to patients needing help with energy and travel costs.

Macmillan is an established part of the UK’s voluntary fabric and traditionally one of its most effective and popular fundraisers, consistently pulling in more than £200m a year from legacies and money raised by tens of thousands of participants in events ranging from marathons, hikes and bike rides to its signature coffee mornings.

But its heavy reliance on charity fundraising has been exposed by soaring inflation and a surging demand for advice and support from rising numbers of people needing help to cope with the financial and psychological consequences of cancer diagnoses and long waits for NHS treatment.

It said in a statement: “Like many organisations, Macmillan has felt the impact of a difficult financial environment. It is getting harder to raise money, and inflation means it costs more to do the same as we did a few years ago. We are tackling these challenges by transforming, so we can have more impact for people with cancer, but without relying on raising more money to be able to do that.

“This has meant taking the difficult decision to reduce the size of the organisation and sadly means we must make some valued colleagues redundant. We are taking these difficult decisions, and building a new strategy to ensure Macmillan is in the best possible position to provide the vital support people living with cancer need now and long into the future.”

A Macmillan spokesperson said it had sought to “minimise the impact” of the cuts on beneficiaries living with cancer. While the job losses were organisation-wide, they would not hit staff providing advice and support direct to the public. The vast majority of the clinicians it funds are employed by the NHS.

The move has shocked the voluntary sector because the biggest charities have been largely resilient to the cost of living crisis, unlike smaller organisations, which are often at the mercy of donor fatigue and council funding cuts. “It’s a surprise. Most big charities are hiring rather than shedding jobs,” one analyst said.

A Macmillan staff member told the Guardian the latest round of cuts had created a “horrible atmosphere” and questioned whether the management had taken its eye off the ball of its core fundraising role. “A lot of good people will be losing their jobs,” they said. “It’s all pretty grim.”

The job losses come three years after Macmillan Cancer Support culled 300 jobs during the pandemic, as it prepared to lose tens of millions of pounds in income as a result of the lockdown cancellation of thousands of fundraising events.

Although fundraising income picked up after the Covid lockdowns ended, the charity faces underlying financial challenges. It spent more than it made in donations in four out of the past five years, and has more than once drawn heavily on dwindling financial reserves to balance its books and meet the rising demand for services.

Its latest financial accounts for the year to 31 December 2022, published in October, showed the charity’s income had dipped from £231m to £227m, partly as a result of declining donations as rising living costs hit donor pockets. At the same time, spending on staff, overheads, grants and services rose to £252m.

Of Macmillan’s income, 97% comes via fundraising and legacies. It raised £204m this way in 2022, down £6m year-on-year, and lower than pre-Covid levels. Fundraising is understood to have flatlined over the past year.

Macmillan Cancer Support has topped YouGov’s annual charity rankings – that measure which charities the public would be most likely to donate to – for 11 years in a row, ahead of other household names such as Cancer Research UK and the British Heart Foundation.

The charity’s chief executive, Gemma Peters, who joined just over a year ago, has described Macmillan’s culture as “quite clunky, siloed and a bit too hierarchical”. She last year launched a major strategy review to re-examine its role, structure and priorities, including its heavy reliance on charity fundraising.

Sarah Vibert, the chief executive of the National Council for Voluntary Organisations, said: “Charities of all sizes are facing a triple threat of record demand, falling income and rising operational costs – with none of these showing signs of letting up anytime soon.”