In Switzerland, basic health insurance is mandatory for all inhabitants, but a rising number of insured have arrears in premium payments, potentially leading to coverage suspension. We aimed at characterizing insured with debt enforcement proceedings with respect to socio-demographic and health utilization aspects. Methods: Cross-sectional analysis of 508.000 insured with basic health insurance contracts in 2013, of whom 14,000 (2.8%) with debt enforcement proceedings, from 11 Swiss cantons. Groups were characterized using logistic regression and latent class analysis. Results: Insured with debt enforcement proceedings were more likely to be young, male and without dependents (partner, kids). Having no supplementary insurance and receiving partial premium subsidies was associated with an increased debt enforcement proceedings risk.Within the debt enforcement proceedings group, three subgroups were identified: 60% were young and seemingly healthy, with a below-average fraction of premium subsidy recipients (18%) and low out-of-pocket payments in prior year (median Swiss Francs 0).Two groups consisted of relatively ill elderly persons (22%, 99% of whom with chronic illnesses) or families (18%), many of whom (29% and 51%) were recipients of premium subsidies. Median out-of-pocket payments in the prior year were high (Swiss Francs 625 and 688, respectively). Conclusions: Sixty percent of premium arrears derive from young insured without apparent financial problems; 40% are owed by elderly and families, which are potentially hurt by coverage loss.