18.104.22.168 There are numerous differences in the post-death treatment of trusts, on the one hand, and decedent’s estate, on the other. These differences can be largely avoided if an election under I.R.C. Sec. 645 is made to treat the trust as an estate (see below). Therefore, any review of the post-death differences should be against the backdrop of whether a Section 645 election should be made.