The 1099 is in the decedent's ssn. After splitting the income between pre / post death, how do I indicate on the 1041 it is a nominee account?

[M-MTax]

You put the entire amount on the decedent's return and subtract out the amount that belongs on the 1041. You then put the amount that belongs on the 1041 as having been paid by the decedent. In other words, the 1041 did not receive the interest as nominee.....the decedent did.

[DaveF1006]

In answer to your question, a nominee trust account is a simple trust  where the trustee acts as the legal owner of some property but is under no obligation to manage the trust fund other than as directed by the beneficiary, and where there are no restrictions beneficiary's right to use the property. So when you set this up under trust information, you will indicate this is a simple trust and that is a same as a nominee trust account.

Please note, if this is the final year or tax return for the trust, this switches to a complex trust. Please see the screenshot I have included below.

[M-MTax]

I'm not sure why you answered in the fashion you did, @DaveF1006, but no one mentioned a trust. What seems to be happening here is simply that the decedent was issue a 1099 covering the year of death for the entire year, obviously including that part of the year which the decedent had passed. Now, the income needs to be divided between the decedent and the decedent's estate. You do that by reporting the entire amount on the 1099 on the decedent's final return and then indicating that part of the income reported was received as NOMINEE for the estate. The estate then reports the post-death share. ALSO, for your information a nominee trust is usually established for holding title to real estate and is a grantor trust.