Autistic individuals are often thought to exhibit reduced tolerance for change, which may stem from atypicalities in sensory processing, particularly in the detection of environmental changes. Within the predictive coding framework, this intolerance may reflect altered generation and updating internal predictions in response to sensory input, leading to increased prediction errors. Mismatch Negativity and the P3a component, event-related potential markers of automatic auditory change detection and involuntary attention shifts, index these processes. While studied in autistic children and young adults, little is known about how these components evolve during aging, an important gap as 21 million autistic adults over 60 are expected by 2050. This study examined mismatch negativity and P3a responses in 43 autistic adults (aged 21–64) and 60 non-autistic adults (aged 20–69) using a passive auditory oddball paradigm with standard (1000 Hz) and deviant (1100 Hz; p = 0.15) tones. Electroencephalography recording revealed no significant differences between autistic and non-autistic individuals on mismatch negativity and P3a amplitude or latency. However, mismatch negativity amplitude decreased with age over frontal site, similarly across both groups. No age-related effects were found for mismatch negativity latency or P3a measures in either group. These findings suggest that, from adulthood onward, the neural mechanisms underlying automatic change detection and pre-attentional processes are similar in both autistic and non-autistic adults, and that their overall time course of aging appears comparable, supporting the parallel aging hypothesis. Nonetheless, future research should explore how these preserved neural responses relate to behavioral reactivity to change in autism.