The only tax that will be associated with the distribution of those accounts are the interest income that the account has earned since the passing of your father-in-law. The Federal Estate Tax exemption is over 5 million dollars and Wisconsin no longer has an estate tax.
I would guess that the accounts have only earned a few dollars in income since the passing of your father-in-law, therefore there will be reportable income of those few dollars. That income will be added to your normal income for income tax purposes.
There are no other taxes that would apply here.
I cannot provide you with legal advise. I can provide you with information about the law related to your question. My answer, and any information that you can find online, should not take the place of having a detailed consultation with a lawyer in your area to advise you regarding your specific issues.
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