How much of my BAOT membership fee goes to UNISON?

BAOT pays a block rate to UNISON centrally for all BAOT members based on it’s membership numbers. There isn’t a set portion of each membership fee that goes to UNISON for trade union services.  
Membership of BAOT buys the whole package which includes full membership of the COT and UNISON.
Members can obviously choose whether or not to take advantage of all services on offer, but there is no reduction in the subscription if they do not.