Argentina (B), Bolivia, Brazil, Paraguay, Uruguay (NB).
Breeds in Andes of western Bolivia (southern from La Paz) and western Argentina (south to Neuquén and western Rio Negro); migrates east, as far as coast in south-eastern Brazil and Uruguay, and as far northern as north-central Bolivia (southern Beni).
 
Population
Estimated population is unknown (2010).
White-bellied Tyrannulet (Serpophaga munda) [XC273315]
by Ana Laura Sureda from North of Cafayate, Salta, Argentina (song)
White-bellied Tyrannulet (Serpophaga munda) [XC461909]
by id from Quebrada San Lorenzo, Capital, Salta, Argentina (call, song)
Subspecies
No subspecies.
Taxonomic status controversial. Sometimes considered a subspecies of White-crested Tyrannulet (Serpophaga subcristata), but the two differ in plumage, also slightly in voice, and in Argentina are narrowly parapatric with limited hybridization. Further study is required. Described taxon Serpophaga griseiceps, from Bolivia (Cochabamba), with reduced white in crown and more buffish wingbars, widely believed to be based on juvenile specimens of present species, and thus treated as synonym of it, but now considered by some to represent a separate species on grounds of voice, plumage and distribution. Further research is required.