Yes, I know, checking your retirement plan beneficiaries is tedious, but if you haven't done so recently (let's say, in the last five years), now's the time. This applies to all your retirement plan accounts, whether 401(k)s, 403(b)s, or IRAs. Your circumstances or those of your named beneficiaries may have changed, meaning that you need to adjust who you name as beneficiaries of your plans.
Or your employer or the investment house in which you hold your accounts may not be able to locate your beneficiary designations. That would be fine if the personal representative of your estate had a copy, but in the absence of a record, the accounts will pass to your probate estate. There are two problems with this:
First, it's more cumbersome and expensive and everything takes more time.
Second, the accounts will have to be liquidated more quickly and the taxes on them paid more quickly and potentially at higher tax rates.
So, check your designations. Keep copies where you can find them. And let your personal representative know where they are.
And Don't Forget Your Life Insurance Policies
While you're at it, check the beneficiary designations on your life insurance policies as well. Again, who you named originally may longer be appropriate (or even alive). And in the absence of a beneficiary, the insurance will be payable to your estate. That has fewer negative repercussions than retirement plans payable to your estate, but still can delay and add cost to your beneficiaries' receipt of the funds — funds they may really need at the time.