for all periods presented , a portion of the balance at end of year pertains to state tax liabilities , which are presented before any offset for federal tax benefits . the effect of unrecognized tax benefits , if recorded , that would impact the annual effective tax rate for 2015 , 2014 , and 2013 would be approximately 12% ( 12 % ) , 4% ( 4 % ) , and ( 1 ) % (  % ) , respectively , of pretax book income ( loss )