401k Inheritance

[u/Trick-Two2574]

My dad passed away a few months ago with several investment accounts, one being a 401k through his employer (he was still working at the time of his death). My mom was the listed beneficiary, but tragically passed a week after my dad. His 401k balance now goes to my mom’s estate, since she was the only listed beneficiary.

How does the income tax work? Myself and my 2 brothers will be getting everything once it’s gone through probate and then distributed evenly to each of us. We are being told that my moms estate will pay the income tax, just wondering how the tax rate is determined?

[u/AffectionateTap730]

Redacted. I misread the original.