401k Participation Highlighted in the Offer Letter. Savvy Human Resource Executives and Talent Recruiters are ahead of the curve. Forward-thinking HR professionals have revised their communication strategy by showcasing their organization’s 401k retirement plan well in advance of a new hire’s first day at work. In a time where new hires must wait for 30, 90 or 180 days before being eligible for or Medical, Dental and Vacation Benefits corporate recruiters are communicating the company’s 401k plan within the text of the official Offer Letter they send to potential employees. If new hires are immediately eligible for participation in your company 401k plan with a 50% match, then put it in writing. Let the new candidate incorporate your firm’s generous retirement plan into their acceptance decision.