Under U.S. federal income tax rules, property you receive as an inheritance—such as cash, real estate, or investments—is generally not treated as taxable income to you. The Internal Revenue Service lists gifts, bequests, and inheritances among common items that are nontaxable to the recipient.
That does not mean every dollar tied to an inheritance is tax-free forever. Income the assets produce after you inherit them—interest, dividends, or rent, for example—is usually taxable. Separate rules can also apply to income in respect of a decedent (amounts the decedent had a right to receive but had not yet received) and to capital gains if you later sell inherited property.
Source: IRS Publication 525 (Taxable and Nontaxable Income); see also the IRS overview that gifts and inheritances are generally tax-free to the recipient at IRS.gov/newsroom.