  I review several scenarios of magnetar formation in binary systems via
spin-up of a progenitor due to interaction with its companion. Mostly, these
evolutionary channels lead to formation of isolated magnetars, and indeed, all
well-established sources of this class are single objects. However, some
binaries can survive, and several candidates to accreting magnetars have been
proposed. I discuss this issue, and conclude that new accretion models can
explain properties of the proposed candidates without large magnetic field in
correspondence with models of magnetic field evolution.
