Personal carbon allowances (PCAs) can complement current carbon pricing policies to achieve the sharp cut in emissions needed to meet the climate targets set by the Paris Agreement. While their effectiveness crucially depends on their social acceptability, there is little evidence on which specific characteristics of their design are preferred by citizens and how these preferences might differ within a society. Our study aims at eliciting preferences for a specific PCA scheme and explores their heterogeneity, using a discrete choice experiment among Belgian citizens and analyzing mixed logit and latent class models. Discrete choice experiments are a widely used tool to deliver key insights to policy design, but have rarely been used in the context of a PCA design. We find that intergenerational differences are important factors to explain citizens’ willingness to accept a PCA, with younger people strongly in favour. A PCA that includes carbon price regulations and provides tailor-made advice on how to reduce carbon emissions, is more likely to be accepted. However, purchase limits for emission thresholds beyond which a tax is imposed should be carefully introduced, as we find large heterogeneity across citizens’ willingness to accept this. These differences are correlated with current emission and income levels, and awareness about PCA. Our study is a first step in designing and developing a PCA, as investigating its social acceptability is a prerequisite before actual implementation.