  In this note we revisit the upper endpoint estimates for commutators
following the line by Harboure, Segovia and Torrea. Relying upon the suitable
BMO subspace suited for the commutator that was introduced by Accomazzo, we
obtain a counterpart for commutators of the upper endpoint extrapolation result
by Harboure, Mac\'ias and Segovia. Multilinear counterparts are provided as
well.

Classical Analysis and ODEs