Biscutate Swift occurs in eastern Brazil, from Piaui and Rio Grande do Norte south to Rio Grande do Sul (Sick 1997), and in northeastern Argentina in Missiones (Pearman et al. 2010). There also is a sight record from Paraguay (Capper et al. 2001).
Biscutate Swift clearly is migratory within portions of its range, but its movements and seasonality remain poorly documented. In northeastern Brazil it is only reported as a nonbreeding visitor, during the austral winter (February-October) (Sick 1991), but it is resident in southern Brazil (Pichorim and Monteiro-Filho 2010).