Mississippi Code Title 89. Real and Personal Property § 89-22-15

(a) The survivorship interest in property held as a tenancy by the entirety to which the survivor succeeds by operation of law upon the death of the cotenant may be disclaimed as provided in this chapter. For purposes of this chapter only, the deceased tenant's interest in property held as a tenancy by the entirety shall be deemed to be an undivided one-half ( 1/2 ) interest.

(b) A disclaimer under subsection (a) takes effect as of the death of the deceased tenant to whose death the disclaimer relates.

(c) The survivorship interest in property held as a tenancy by the entirety disclaimed by the surviving tenant passes as if the disclaimant had predeceased the tenant to whose death the disclaimer relates.