IRS Publication 525 Taxable and Nontaxable Income, on page 32, outlines different forms of inheritance:

Gifts and inheritances. In most cases, property you receive as a gift, bequest, or inheritance isn't included in your income. However, ifproperty you receive this way later produces income such as interest, dividends, or rents, thatincome is taxable to you. If property is given toa trust and the income from it is paid, credited,or distributed to you, that income is also taxableto you. If the gift, bequest, or inheritance is theincome from the property, that income is taxable to you.

Inherited pension or IRA. If you inheriteda pension or an IRA, you may have to includepart of the inherited amount in your income.See Survivors and Beneficiaries in Pub. 575 ifyou inherited a pension. See What if You Inheritan IRA? in Pubs. 590-A and 590-B if you inherited an IRA.

Expected inheritance. If you sell an interest in an expected inheritance from a living person, include the entire amount you receive ingross income on Schedule 1 (Form 1040),line 8.

Bequest for services. If you receive cashor other property as a bequest for services youperformed while the decedent was alive, thevalue is taxable compensation.

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