Using joint tenancy as an estate planning device is straight-forward and inexpensive. But proceed with caution.
To see how joint tenancy is easy to do but not so easy to un-do, let's look at a real-life example.
Mom wants to do some inexpensive estate planning. She is 60-yrs old, single, and has an adult daughter. Her house, which is paid for, is her major asset. The house is currently owned by her alone. She wants the house to go to her daughter at her death.
Mom decides to record a deed to the house in joint tenancy with her daughter. She does this as part of a do-it-yourself estate plan.
Since Mom wants the house to pass to her daughter at her death, she knows that a house titled in joint tenancy will pass to the joint tenant. She records a new deed to the house: "Mom and Daughter, joint tenants with rights of survivorship".
Much time goes by and over the years daughter becomes very prosperous and ends up owning a home locally, a place in Palm Springs, and some rental property as well. Now that a lot of time has gone by, Mom's favorite nephew is not doing well financially. Mom changes her mind about the house. Daughter doesn't need the house. Mom would now like it to go to the nephew at her death.
If daughter agrees that the joint tenancy can be undone, fine. But if daughter does not agree, Mom cannot change the arrangement. Because daughter now owns an interest in the home, Mom cannot change the titling without daughter's permission.
So the lesson here is that years go by, things change. To untangle a joint tenancy arrangement, all parties must agree.