Why do I need consent of my spouse when I want another party as beneficiary of my 401k or take a distribution?
Answer: A Spouse has an interest in your 401k and before that interest is given up -- as with a beneficiary change or withdrawal -- they must agree.
Spousal consent rules with respect to qualified plans stem from the Retirement Equity Act of 1984 (REA). As a general rule, married participants must receive the written consent of their spouse prior to taking distribution from a qualified plan in a form other than a qualified joint and survivor annuity (QJSA).
401k plans may be drafted as a so-called "REA Safe Harbor Plan" (thereby exempting it from the QJSA requirements). However, in such cases, the spouse must generally consent in writing to the naming of anyone other than the spouse as primary beneficiary.