When a loan is being assumed, in addition to an Assumption Deed, the Seller should require the Buyer to sign a Deed of Trust to Secure Assumption. In a deed of trust to secure assumption, another person assumes the note already in place, guaranteeing payment to the grantor in the deed.A deed of trust to secure assumption is used to grant property rights when there is an existing mortgage or similar home finance loan. Deeds of trusts are "a deed conveying title to real property to a trustee as security until the grantor repays a loan. A Deed of Trust in Texas transfers title of real property in trust. It is the equivalent to a mortgage used in other states and provides a secured interest. B. Short Form Deed of Trust. Read the instructions thoroughly. In Texas, any agreement (whether a deed of trust or trust deed) creating a security interest in real property as an incident of a debt constitutes a mortgage. A deed of trust is not a deed.