PurposePrevious research has shown that self-employed workers are more likely than employees to retire late or to be uncertain about retirement timing. However, little is known about the underlying mechanisms. This study aims to fill this gap, by focusing on the explanatory role of various job characteristics – flexibility, autonomy, skills-job match and job security – for explaining differences in retirement preferences between the solo self-employed and employees.Design/methodology/approachData were used of 8,325 employees and 663 solo self-employed respondents (age 45–64) in the Netherlands, who participated in 2016 in the Study on Transitions in Employment, Ability, and Motivation (STREAM). The outcome variable distinguished between early, on-time, late and uncertain retirement preferences. Multinomial logistic regression models were estimated, and mediation was tested using the Karlson-Holm-Breen (KHB) method.FindingsThe solo self-employed are more likely than employees to prefer late retirement (vs “on-time”) and to be uncertain about their preferred retirement age. Job characteristics mediate 21% of the relationship between solo self-employment and late retirement preferences: the self-employed experience more possibilities than employees to work from home and to choose their own working times, which partly explains why they prefer to retire late.Originality/valueIn discussions about retirement, often reference is made to differences in retirement savings and retirement regulations between the solo self-employed and employees. The current study shows that differences in job characteristics also partly explain the relatively late preferred retirement timing of solo self-employed workers.