Testamentary trust.

If you had a testamentary trust.  You could not elect 645 and file the trust with the estate under the same Tax ID?   If so, do you file 2 returns or do you just file the trust return while probate is going on? Trust came into effect at death? 

 

if you do estate, then does that transfer to a trust?  What about the terminal deductions from the estate?  

Would you ever have an estate final year and then a trust final year years later?   


Or would you have a decedent income tax return and an estate tax return then continuing with a trust 1041?