There is a number that the Treasury keeps returning to, and it is becoming harder to explain away. Around 2.8 million people in Britain are currently out of work due to long-term sickness, a figure that has climbed, almost without pause, since the start of 2020. According to the Office for National Statistics, long-term sickness is now the single largest reason for economic inactivity among working-age adults in the UK, overtaking retirement, caring responsibilities and study. That is a significant structural shift, and I’d argue we are only beginning to reckon with what it means.
The conditions driving this surge are not the ones you might expect from a Victorian-era conception of workplace incapacity. This is not a story about industrial accidents or occupational lung disease. The fastest-growing categories are mental health conditions, chronic pain syndromes and post-viral illness, including Long Covid. Put simply, Britain’s workforce is becoming less healthy in ways that are difficult to see, difficult to measure and, for those experiencing them, frequently disbelieved.
What the DWP and ONS figures actually show
The Department for Work and Pensions publishes regular statistics on health-related benefits, and the trajectory is stark. Claims for Personal Independence Payment and its predecessor Disability Living Allowance have risen sharply, with mental and behavioural disorders now accounting for around 35% of all new PIP claims. The ONS Labour Force Survey, which captures economic inactivity more broadly, shows that the share of 16-to-64-year-olds citing long-term illness as their reason for not working has risen by roughly a third since 2019.
What makes this particularly thorny for policymakers is the age distribution. This is not exclusively a crisis of older workers approaching retirement. A substantial and growing proportion of those leaving the workforce due to ill health are in their thirties and forties. The Resolution Foundation estimated in late 2024 that the UK has a higher rate of working-age economic inactivity due to ill health than comparable European economies, including France, Germany and the Netherlands. That gap is widening, not narrowing.
I’ve spoken to several GPs and occupational health specialists over the past year, and the picture they describe from inside consulting rooms is consistent with the headline data. Waiting lists for mental health services remain long enough that people deteriorate before they receive treatment. Chronic pain, which the British Pain Society estimates affects around 28 million adults in the UK, is still treated with considerable scepticism in both clinical and workplace settings. And Long Covid, affecting an estimated 1.8 million people according to ONS self-reported data from 2025, has created an entirely new cohort of working-age adults unable to sustain full-time employment.
Why mental health conditions are driving the headline numbers
Anxiety, depression and related conditions have become the dominant diagnostic category within long-term sickness UK workforce inactivity, and the reasons are not difficult to identify even if the remedies are elusive. The pandemic, the cost-of-living crisis and years of wage stagnation have created conditions under which mental health problems flourish. The NHS mental health waiting list in England alone ran to over 1.6 million people earlier this year.
The problem is self-reinforcing. When someone leaves work due to depression or anxiety, the loss of routine, social contact and financial security tends to deepen the original condition. Getting back into employment becomes harder with each passing month. The DWP’s own commissioned research has found that the longer someone is out of work due to mental illness, the less likely they are to return, regardless of the support they receive. This is a feedback loop that current policy instruments are poorly designed to break.
There is also a class dimension that rarely receives the attention it deserves. Mental health conditions are more prevalent and more severe among people in lower-income households, those in insecure employment and those who have experienced housing instability. The idea that long-term sickness is distributed evenly across the workforce is simply not supported by the data. Those whose jobs offer flexibility, autonomy and adequate sick pay are considerably more likely to recover and return. Those whose jobs offer none of those things are considerably more likely to fall off the employment cliff entirely.
The public finances arithmetic is brutal
The fiscal consequences are substantial. The Office for Budget Responsibility has repeatedly flagged health-related inactivity as a structural risk to the public finances, and for good reason. Each person who moves from employment to long-term sickness inactivity represents a swing in the government’s accounts: lost income tax and National Insurance receipts, plus the cost of health and disability benefits. The OBR estimated in its most recent Fiscal Risks report that the welfare bill relating to health conditions could rise by tens of billions of pounds over the next decade if current trends persist.
Ministers have talked about reforming the work capability assessment and tightening eligibility for health-related benefits, and there is a real debate to be had about whether the current system creates any perverse incentives. But the people I’ve read about and spoken with who have left work due to chronic pain or severe anxiety are not, in the main, gaming a system. They are, by and large, genuinely unwell in ways that make sustained employment impossible without proper treatment and workplace accommodation. Cutting their income does not cure their illness; it simply makes them poorer and sicker.
The more honest question is whether the UK’s healthcare infrastructure is capable of treating these conditions at the scale now required. The NHS’s Talking Therapies programme has expanded, but referral-to-treatment times for more complex mental health presentations remain long. Occupational health provision is largely absent from small and medium-sized employers, who collectively employ the majority of the private-sector workforce. And post-viral illness services have been chronically underfunded relative to the scale of the problem they are supposed to address.
What a serious response would look like
A genuine strategy to reduce long-term sickness UK workforce inactivity would need to operate on several fronts simultaneously. Earlier clinical intervention, before conditions become entrenched, is the most obvious lever. Expanding access to occupational health assessment, particularly for workers in small businesses, would help retain people in work before they reach crisis point. Reforming statutory sick pay so that lower-paid workers are not financially compelled to return to work before they are ready would reduce the number of people who deteriorate after a premature return.
Flexible working, which has been shown to support people with chronic conditions, should be a meaningful right rather than the nominal one it currently is. The challenges facing older workers managing health conditions have been well-documented, and the same workplace adaptations that benefit those in their sixties are equally valuable for someone in their forties managing chronic pain. There is also a conversation to be had about the quality of work on offer. Precarious, high-pressure, low-autonomy employment is itself a driver of the mental health conditions that are now emptying the workforce. You cannot solve a public health problem by ignoring its structural causes.
The broader context matters here too. Britain’s working-age population is becoming less healthy against a backdrop of a pension system already under significant strain and a welfare state that is not designed to absorb this volume of need. And as explored in our recent piece on developmental disruption in schools, many of the risk factors for poor adult mental health are being set in childhood. The sickness crisis in the workforce is not a discrete policy problem. It is a symptom of something larger and considerably harder to fix.
I am not optimistic that the current political environment, with its focus on benefits reform and fiscal consolidation, will produce the sustained investment that a genuine solution requires. But the data is unambiguous. Britain is losing hundreds of thousands of working-age people to preventable and treatable conditions, at enormous cost to those individuals and to the public finances. Looking away from that because the conversation is uncomfortable is no longer a viable position.
Frequently Asked Questions
How many people in the UK are out of work due to long-term sickness?
Approximately 2.8 million working-age adults in the UK are currently economically inactive due to long-term sickness, according to ONS Labour Force Survey data. This figure has risen substantially since 2019 and represents the single largest category of economic inactivity.
What conditions are most commonly behind long-term sickness UK workforce inactivity?
Mental health conditions including anxiety and depression are the fastest-growing category, followed by musculoskeletal problems and chronic pain. Post-viral illness, particularly Long Covid, has added a significant new cohort since 2020, with ONS estimating around 1.8 million people in the UK reporting Long Covid symptoms in 2025.
How much does long-term sickness inactivity cost the UK public finances?
The Office for Budget Responsibility has flagged health-related inactivity as a structural fiscal risk, estimating the welfare bill for health conditions could rise by tens of billions of pounds over the next decade. The cost includes both reduced tax receipts and increased spending on disability and health benefits.