Bangladesh, Bhutan, China (mainland), India, Myanmar, Nepal, Pakistan.
Breeds Himalayas from northern Pakistan (Gilgit, Hunza, Baltistan) and Kashmir east to south-western and central China (southern and eastern Xizang, and eastern Qinghai and central Gansu south to northern Yunnan and north-eastern Sichuan). Non-breeding south-eastern Nepal and central, south-western and north-eastern India east to southern China (south-eastern Xizang, western Yunnan, Guizhou), north, central and eastern Myanmar and north-western Thailand.
 
Population
Estimated population is unknown (2010).
Tickell's Leaf Warbler (Phylloscopus affinis) [XC191453]
by Mike Nelson from Haixi, Qinghai, China (song)
Tickell's Leaf Warbler (Phylloscopus affinis) [XC547646]
by Ding Li Yong from Lokat Bangus (Little Bangus Valley), Jammu and Kashmir, India (song)
Subspecies
Has often been treated as conspecific with Buff-throated Warbler (Phylloscopus subaffinis), but recent studies have revealed constant vocal differences (and differences in responses to songs) between the two.
Considered by some authors to be a subspecies of White-spectacled Warbler (Phylloscopus intermedius).
The following 2 subspecies are recognised:
affinis (Tickell, 1833) - Himalayas. Considered by some authors to be a subspecies of White-spectacled Warbler (Phylloscopus intermedius).
perflavus Martens, J, Sun & Päckert, 2008 - Western Himalayas; winter range not known (overlaps with nominate affinis?).