409aadvantagesavoidbusinesschangescodecommoncompaniescompanyconsiderationsdeferredearlyemployeesemployersemploymentequityexemptionhandbookimpactincentiveknowlawsmaymitigatingnavigatingneednuancesoptionspensionpitfallsplanplanspreparingqpamrepricingrequirementssectionstartupsstatestockstructuretechtoptransactiontransactionsusworkforce