This research problematises mathematics teacher knowledge for teaching the Financial Mathematics topic to learners who come from communities where the time-value of money and a banking culture is not well established. The COACTIV framework underpins the study to build a pedagogical framework to teach Financial Mathematics to such learners. Data was collected from a sample of 20 South African mathematics teacher educators and business studies lecturers who teach Financial Mathematics at tertiary levels using a questionnaire. Focus were also held with participants to corroborate the results. The results of the study showed that many learners come from cultures that do not hold a time-value-of-money construct and do not readily learn textbook Financial Mathematics because it is not attuned to their home backgrounds. A pedagogical framework that takes into account learners' cultural knowledge systems is suggested to teach the topic, particularly to learners from disadvantaged communities.