i have a sub 50 amp sub panel that i want to put in a detached maint/gar building.
to save money on wire i am going to run two #6's for the lines and one #8 for the neutral(derating the neut)along with a #10 ground. my question is does this sound code compliant, we derate neutrals for the service feeders and this is going to be a feeder so it seems very complicit to me.

am i on the right page? any codes that i am missing which would forbid this derating?
thanks guys,
h20