When organisations think about the cost of poor mental health, they often focus on sickness absence. While absenteeism is visible and easy to measure, it represents only part of the financial impact. The biggest costs are often hidden in reduced productivity, increased staff turnover and the expense of replacing experienced employees.

According to Deloitte's latest UK research, poor mental health costs employers an estimated £51 billion every year. Surprisingly, absenteeism accounts for only around £7 billion of this figure. The largest cost is presenteeism—employees coming to work while struggling with their mental health but performing below their usual capability—which costs UK businesses approximately £24 billion annually. Staff turnover linked to poor mental health contributes a further £20 billion. These figures demonstrate that the greatest business risks are often the least visible.

The impact extends beyond financial reporting. The UK's Health and Safety Executive estimates that work-related stress, depression and anxiety resulted in 17.1 million working days lost in 2022/23, affecting around 875,000 workers. Lost working days disrupt projects, place additional pressure on colleagues and reduce customer service levels, creating a ripple effect across organisations.

Recruitment and retention add another layer of cost. When employees leave because of prolonged stress or burnout, employers face advertising costs, recruitment fees, onboarding expenses and the time required for new staff to become fully productive. Valuable organisational knowledge is also lost. Replacing an experienced employee is almost always more expensive than supporting them before they reach crisis point.

Many organisations invest in wellbeing initiatives, yet overlook one of the most practical interventions: equipping people with the confidence to recognise when a colleague may be struggling and to start supportive conversations early. Early intervention can encourage employees to access appropriate support before problems escalate into long-term absence or resignation.

The business case is compelling. Deloitte's analysis found that, on average, employers receive £4.70 for every £1 invested in effective workplace mental health support, with the strongest returns coming from preventative measures such as education, awareness and culture change rather than waiting until employees become seriously unwell.

Poor mental health is therefore not simply a wellbeing issue—it is a productivity, retention and business performance issue. Organisations that invest in developing mental health awareness and skills are investing in a healthier workforce, stronger organisational resilience and better long-term performance.