Recently, economists have used notions of linguistic relativity to suggest that grammatical constraints on Future Time Reference (FTR) affect whether people choose to take a small reward now or wait until later for a larger reward ("temporal discounting"). Economists hypothesize that habitual use of present tense constructions for FTR may cause speakers to perceive future rewards as temporally closer, and thereby as more valuable. This approach assumes that future tenses primarily encode when an event happens, which overlooks their widespread tendency to encode modal notions of probability. It additionally overlooks the importance of modal expressions in FTR. Since people discount value as a function of both temporal distance and the probability of a reward being received, it is important to understand what different FTR tenses actually encode, as well as cross-linguistic differences in the grammaticization of modality. We therefore modified the EUROTYP questionnaire to elicit future tense as well as modal FTR constructions across a range of temporal distances and probabilities for speakers of English, Dutch, and German. We find that in English tense and probability are more strictly grammaticized than in Dutch or German, and that increasing temporal distance from speaker "now" tended to cause English and German – but not Dutch – speakers to use more uncertain terms. These results highlight the importance of modality for typological linguists working on FTR, and suggest economists working on linguistic relativity and psychological discounting should consider cross-linguistic differences in the grammaticization of modality and in the modal semantics of future tenses.