Interest earned before the date of death go on the decedent’s return, even if posted and paid later. (There are some special rules for items like savings bonds, but this is the general rule.) Strictly speaking you should ask for a corrected 1099 showing interest accrued to the date of death as earned by the decedent and the rest as earned by the estate. If you don’t get one, you’re supposed to report all the interest on the decedent’s return, but subtract out the amount earned after the date of death as a “nominee distribution,” and report that income on the estate’s return. When I wrote my initial reply, I was thinking the dollar amount would be too small to worry about, but this amount is perhaps enough so you’d want to follow this rule. See page 6 of IRS pub 559.