When, during the administration of the succession, it appears that the surviving spouse will be entitled to the marital portion, he has the right to demand and receive a periodic allowance from the succession representative.
The amount of the allowance is fixed by the court in which the succession proceeding is pending. If the marital portion, as finally fixed, is less than the allowance, the surviving spouse is charged with the deficiency.
La. C.C. § 2437