This article adopts an intersectional lens as an analytical framework to examine how overlapping demographic dimensions, such as age, ability, ethnicity, geography, gender, and home ownership status, shape the diverse experiences of energy poverty among low-income households in Ireland. Despite extensive research on the vertical impacts of carbon taxes across income groups, scholarship examining horizontal impacts on non-income groups remains limited, with few studies employing qualitative methods to investigate intersectional justice implications. Addressing this gap, our study conducted twenty-one semi-structured interviews with key informants to identify vulnerabilities often overlooked in conventional economic analyses. Our findings reveal that while Ireland's carbon tax policy has implemented progressive revenue recycling measures that benefit households in the bottom five income deciles, certain vulnerable groups, particularly renters, Travellers, and disabled persons, are not fully recognised in both policy design and economic modelling. The study demonstrates that qualitative research methods can complement quantitative approaches by uncovering vulnerabilities that are statistically difficult to capture in econometric studies due to data limitations or small sample sizes. We argue that carbon tax policies informed by intersectional analysis can more accurately mitigate adverse impacts on vulnerable populations and foster more equitable transitions to a low-carbon economy. Potentially, this can also improve public acceptability of carbon taxes. This research contributes to the emerging literature on horizontal impacts of carbon pricing and offers insights for policymakers seeking to design more inclusive climate policies that address the complex interplay between carbon pricing and non-income vulnerabilities.