Continuing to study mathematics is currently a requirement for low attaining 16- to 18-year olds in Further Education, as part of an ongoing drive to raise basic numeracy skills in England. However, these students, widely regarded as demotivated, often fail to make any progress in mathematics over the two years. This research explores how students make sense of the complex relationship between the two main post-16 qualifications, GCSE and Functional Skills, and its effect on students' opportunities to succeed in mathematics. The study was conducted with vocational students (N = 187) at one Further Education college in the academic year 2018-19, using both a questionnaire and examination results. Findings suggest multiple dimensions that students valued in mathematics qualifications, while GCSE and Functional Skills were viewed either as a single linear progression or as two divergent pathways. Success was linked to features of the qualification taken, raising questions about inequality of opportunity.