Background There is evidence that changes to the social security system have contributed to the decline in mental health in the UK. The ‘bedroom tax’ (BT), known as the removal of the spare room subsidy introduced in 2013, reduces the amount of housing benefit provided to working age claimants living in social housing in Great Britain who have ‘spare rooms’. There is limited evidence of the effects this change has on mental health. We therefore aimed to evaluate the impact of the BT on mental health of affected claimants.

Methods We used eight waves of longitudinal data from the Understanding Society, UK Household Longitudinal Survey (UKHLS), from 2009 to 2016. Our sample included working age housing benefit claimants living in social housing in Great Britain. People were allocated to the intervention group if they reported living in a household with more bedrooms than their allowed total and allocated to the comparison group if they reported the same or fewer bedrooms than their allowed total. Mental health was measured using the Short Form 12 Mental Component Summary (SF12-MCS) and General Health Questionnaire 12 (GHQ-12). The BT’s effect on mental health were estimated using difference-in-differences (DiD) with mixed effects linear regression models, controlling for covariates (country, age, sex, education, employment, partnered status and health). All analyses were carried out with R version 3.5.1.

Results We analysed 13,882 observations from 5,813 people (n= 1,747 intervention group, n = 4,066 comparison group). Descriptive analysis showed in the year prior to the BT introduction, individuals in the intervention group were more likely to reside outside England, be older, male, partnered, unemployed, have no educational qualifications and have a long-term health condition or disability. Our DiD analysis (-0.62; 95%CI -0.45 to 0.20; p-value 0.139) showed no significant change in mental health (SF12-MCS) in the intervention group following the introduction of the BT in 2013, relative to the comparison group. There was a statistically significant decline in mental health in both groups from 2009 to 2016. SF12-MCS reduced by an average of 0.37 (95%CI 0.22 to 0.52) per year. Results using the GHQ-12 found similar results.

Discussion Contrary to previous evidence, we found no effect of the bedroom tax on mental health. However, both groups experienced a deteriorating mental health over the study time period. This merits further investigation; it is possible that the observed increase in mental distress is a response to wider changes to the social security system occurring at the same time as the BT.