d0bd6e4e__NQDCs____Fidelity_Investments__401_k_
[Feature] Flexibility in when and how the participant can withdraw money in retirement [NQDC] Limited by up-front elections, plan provisions, and redeferral rules [401(k)] 
Usually, but not required
Nonqualified Deferred Compensation Plans (NQDCs) - Fidelity Investments