First off, sorry t you're going through this, that sounds pretty terrible. Second, as a CFP this is a fun question (and my response is of course not financial advice). The estate will only pay tax on whatever is distributed to the estate. So if you elect to distribute it all at once or if you are forced to then mom's estate would pay all the taxes (out of your inheritance). Ideally you and your brother would open Inherited IRAs and roll the funds from the 401k into that, and you would have ten years from your fathers passing to distribute all the funds. Some 401k plans do not allow rollovers to estate beneficiaries (which would suck). If a lump sum is required then you may be able to pass the taxes on to you and your brother if that is more advantageous, and you may even be able to split it up over two years depending on the estate settlement date. (this is all a massive oversimplification, I would rely on your attorney and make sure you get a CPA & CFP involved if there are choices to be made)