To preserve the ability to stretch IRA distributions for a beneficiary, that individual must start taking withdrawals based on his/her life expectancy in the year after death. If those required withdrawals don't start on time, can you still rectify the situation to preserve the tax deferral?
The good news is that recent private letter ruling 200811028 (and more recently, IRS Information Letter 2016-0071) indicates the answer is "yes."