This article sets out to elucidate the factors that add to the use of the Korean subject honorific -(u)si—, a long-standing matter in the study of pragmatics and politeness in that language. Two groups of Korean speakers (younger versus older adults) were examined on two patterns of honorification: (a) the classic pattern in which the referent of the subject outranks both the speaker and the hearer, and (b) the split pattern in which the referent of the subject outranks the speaker but not the hearer. In an online acceptability judgment task, younger participants (n = 40) displayed a potent and quick predilection for the use of -(u)si in the classic pattern, yet showed doubt in the split pattern. In contrast, older participants (n = 40) displayed a notable predilection for -(u)si in both the split pattern and the classic pattern when the referent of the subject outranks the speaker.