If you're talking about a trust return, then you can just enter the box 8 Original issue discount on U.S. Treasury obligations as normal interest on line 1 of Form 1041.
Please see Line 1—Interest Income in the Instructions for Form 1041 and Schedules A, B, G, J, and K-1 for more information.
The box 8 OID is exempt from state and local income taxes, and isn't included in box 1 of Form 1099-OID. However, it must be reported on the federal income tax return. See Box 8 in the Instructions for Recipient on the back of Form 1099-OID.
See also Publication 1212, Guide to Original Issue Discount (OID) Instruments for information on any adjustments that may need to be made to the box 8 amount.
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