Among adults with intellectual disabilities (IDs), there is a need not only to assess financial decision-making capacity, but also to understand how it can be maximized. Although increased financial independence is a goal for many people, it is essential that individuals decision-making abilities are sufficient, and many factors may affect the development of such abilities. As part of a wider project on financial decision-making, we analysed previous data from a group of 30 adults with mild IDs, identifying correlations among four variables: (i) financial decision-making abilities; (ii) intellectual ability; (iii) understanding of some basic concepts relevant to finance; and (iv) decision-making opportunities in everyday life. Results The analysis indicated a direct relationship between ID and basic financial understanding. Strong relationships of a potentially reciprocal nature were identified between basic financial understanding and everyday decision-making opportunities, and between such opportunities and financial decision-making abilities. The findings suggest that the role of intellectual ability in determining financial decision-making abilities is only indirect, and that access to both basic skills education and everyday decision-making opportunities is crucial for maximizing capacity. The implications of this are discussed.