Literature on the topic of trans older adults has documented a few anecdotal cases in which some trans people living with dementia forgot they transitioned and reidentified with their sex assigned at birth (“detransition”). Trans commu- nities and their allies have encouraged trans people to engage in end-of-life planning, including the preparation of legal documents that state their wishes regarding gender identity and expression in the event of “incapacity” caused by dementia. While useful, we contend that end-of-life planning is often implicitly based on cisnormative and cognonormative (normative system based on cog- nitive abilities) assumptions. Such planning is founded on a stable notion of gender identity throughout the life course (“post-transition”) and assumes that the pre-dementia self is better equipped to make decisions than the “demented” self. We conclude by encouraging, based on an intersectional, trans-affirmative, crip-positive, and age-positive approach, respect for the agency of trans people with dementia.