Final regulations set forth guidance on the application of section 409A to nonqualified deferred compensation plans. The regulations provide a definition of a nonqualified deferred compensation plan subject to section 409A, including rules related to the statutory effective date, and rules governing initial and subsequent deferral elections, the establishment of the time and form of payment, and the acceleration of payments under a plan. Notice 2005-1 obsoleted in part. Notice 2006-4 superseded in part. Notice 2006-64 superseded for taxable years on or after January 1, 2008.