The gross estate may differ greatly from the probate estate. The following items are includible in the gross estate, but not the probate estate, except:

a. Life insurance proceeds payable to the decedent's daughter

b. Joint savings account in the names of the decedent and the surviving spouse

c. Real estate held as community property by the decedent and the spouse

d. Property transferred to a revocable trust by the decedent three months before death