This study analyzed the production and perception data of 112 Taiwanese/Mandarin young bilinguals. It surveyed the latest status of the /iN/ variation of Taiwanese and Taiwan Mandarin and further explored Taiwan Mandarin's influences, if there are any, on Tai-gi /iN/ variation. The results showed that at production level, /in/ variation is ongoing in both Taiwanese and Taiwan Mandarin. /in/ saliently merged to /iŋ/ in both languages with Taipei being more salient than the South and female being more salient than male. On the other hand, /iŋ/ remains rather stable. It is surmised that current performance of Taiwanese /in/ variation is possibly influenced by Taiwan Mandarin /in/ variation, particularly in Taipei, where the speakers performed the /in/ variation in similar manners in both Taiwanese and Taiwan Mandarin. Furthermore, the Taiwanese /in/ words that phonologically overlap with their Mandarin counterparts are more likely to perform the /in/ → / iŋ/ merger. On the other hand, Taiwanese /im/, in addition to the frequently reported / im/→/in/ merger, is undergoing a new variation, /im/→ /iŋ/, further marking the leading status of /iŋ/ in Taiwanese /iN/ production. As to the /iN/ perception test, the study adopted Coach Test as the major methodology. The results indicated that /iN/ perception is more unstable than its production, in both Taiwanese and Mandairn. Most participants had difficulty in judgement. It is suggested that the variants of /iN/ rhyme in both Taigi and Mandarin are likely to develop into near merger