There is no Federal inheritance tax.  Some states do have an inheritance tax and you should check with your state tax website to see if it applies in your particular state.

Some inheritances are subject to Federal income tax, most particularly distributions from qualified retirement plans such as IRAs, pension plans, 401(k)s, etc.  If your distribution is from such a plan, you should receive a Form 1099-R from the trustee which you will have to include in your Federal income tax return.