With financial institutions increasingly transferring products and services online, the interaction of older adults with the web has received some attention. However, research on the accessibility and usability of the language of online financial content for older adults is lacking. Furthermore, evidence on the potential benefits of plain language is needed. We conducted a two-part study to fill these research gaps. First, we conducted a focus group with four older adults to find out: (i) if participants had concerns about the accessibility of online financial texts; and (ii) which types of texts might have benefited from plain language editing in their experience. We observed that older adults regarded Terms and Conditions as difficult to read. In a second stage, we examined the usability of Terms and Conditions through an experiment with 25 older adults. We tested the impact of plain language on different usability components, namely satisfaction ratings, reading comprehension, perceived comprehensibility, and reading behaviour for Terms and Conditions related to direct debits provided by a bank and an insurance company. We found no benefits of plain language on the usability components under investigation. However, despite a general tendency to skim through or read only parts of Terms and Conditions, we also observed that reading behaviour was more varied—including repeated readings, section skipping, and reading abandonment—with texts that had not undergone plain language editing. Furthermore, aspects other than language (such as visual components) were valued by older adults. Conclusions and implications are outlined.