Priv. Ltr. Rul. 201220017 (Jan. 26, 2012)

(decedent's surviving spouse was foreign national that had just become U.S. citizen; prior to becoming citizen, Qualified Domestic Trust (QDOT) created to receive funds from spouse, but IRS not notified of citizenship change; extension of time granted to provide notice due to lawyer for surviving spouse not mentioning that estate tax wouldn't apply to QDOT; good faith reliance present).