Individuals are able to participate in multiple 401(k) plans as long as they adhere to IRS contribution limits, as stated by official IRS guidelines. As of March 2015, an individual can save up to $18,000 a year in a single or multiple 401(k) plans. Individuals 50 or older can save up to $24,000 a year.
If an individual works two jobs that both have 401(k) plans, he can participate in both plans. The sum of contributions from both plans must be under the IRS limit.
It is also possible to have multiple 401(k) plans from previous employers. For convenience, these 401(k) plans can be rolled into one IRA or into a current 401(k) plan, as reported by Forbes.