Things have changed since we "seasoned" preparers first learned about gift/estate taxes. The look-back period now applies only to gifts made TO the decedent, retained life estates and interests, closely held businesses, and a few other oddballs. (See the 706 instructions, pp 26-27). Also, any gift taxes paid within the past three years get added back into the estate. I'm doing one of these right now. Mom gave her sons some stocks she had owned for 50 years; the stock certificates were retitled and legally transferred 4 days before she died. (The process had to start before then.) The step-up basis would have helped them avoid massive cap gains they now face. Thankfully she did not transfer her shares of ATT and its baby bells, and their babies, so the sons get step up on those. It has to be every preparer's nightmare to calculate basis of original ATT shares.