Federal tax has no inheritance tax.

Inheritance tax and estate tax are two different things. Inheritance tax is what the beneficiary — the person who inherited the wealth — must pay when they receive it. Estate tax is the amount that’s taken out of someone’s estate upon their death. One, both or neither could be a factor when someone dies.

https://www.nerdwallet.com/article/taxes/inheritance-tax?

Federal has estate tax. That is, the dead person pays an estate tax on the year he/she dies.  The estate tax exemption is 11 million. 

There is no federal inheritance tax.  There might be inheritance tax on several states. see link above.