Income in Respect of a Decedent, (IRD,) is income that a person has worked for (“earned”) during his or her lifetime, but did not realize for tax purposes due to his or her death. An example would be a 401(k) account with a beneficiary. The beneficiary will be very happy to learn that you left him or her money for future endeavors. However, that same beneficiary will learn that when the money is withdrawn, income taxes will be due at his or her ordinary income tax rate.
The issue with IRD is that the earned income needs to be taxed and does not receive a step-up-in-basis which would have allowed the beneficiary to avoid paying any taxes on the inheritance.
Under our current tax system, heirs receive a basis adjustment on property that they inherit. The basis in property inherited is the fair market value of the property at the time of your passing. Therefore, if you were to purchase stock at $10,000 in 2000, and at your death in 2005 the fair market value of the stock was $20,000, your heirs would have a $10,000 difference, a gain, to report. With the step-up-in-basis rule the heirs would receive that stock and its new value of $20,000, and if they then sold it for $20,000 they would receive that money without having to pay any income taxes. IRD income does not qualify for the step-up-in-basis rule because of its nature of not being realized.
Another bad point to IRD income is that the income taxes paid are in addition to the estate taxes that are also due. The beneficiary will be entitled to an income tax deduction for the estate taxes paid, but the total amount of both taxes is not comparable to the deduction.