This work aims to clarify the definition of financial well-being and make propositions for building a theory of financial well-being by describing and reviewing its theoretical foundations. Although financial well-being's scope is essentially individual, it is necessary to understand it in a broader context due to its social impact and association with socio-economic progress and happiness. We follow a qualitative-descriptive method based on the literature employed in empirical works and the principles enunciated by diverse scholars and institutions. The originality of this work lies in consolidating a financial well-being definition, relating, and contrasting several of its theoretical foundations together instead of addressing them separately. We argue in favor of establishing a theory of financial well-being to define, measure, and analyze it comprehensively. This proposal considers different dimensions such as time, human needs, saving motives, and institutional policies. Our results are of interest to those involved in research about financial well-being, general well-being, and the economics of happiness. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.