"With some creative plan adaptations, plan sponsors can assist employees as they make retirement a real possibility.... [E]mployers will want to consider how many hours per year they expect partially retired workers to work in order to share in the contribution ... Employers who want to encourage older workers to stay employed may consider changing the company contribution so that it is age-weighted ... Partially retired employees with fluctuating income may need more flexibility on how frequently they can change their deferral elections."