Relative income and its relationship with mental health in UK employees: a conceptual and methodological review.

The relative income hypothesis theorises that the earnings of an individual relative to others exert a greater influence on subjective wellbeing than absolute income. Understanding the relationship between relative income and mental health could contribute to employee wellbeing. This review narratively synthesised the defining features and measurement of relative income, and its impact on mental health among UK employees. Systematic searches of qualitative and quantitative research evidence identified 13 studies. A conceptualisation of relative income revealed that an income comparison is either researcher-defined using averages or self-assessed based on the perception of an individual. Having a lower income than the reference group was commonly associated with diminished wellbeing, though moderating factors (gender, income inequality and composition of reference group) are discussed. Implications for practice and policy are considered amidst the cost of living crisis in the UK and ongoing pay disputes in various sectors.