1,261. The Nasi's Approval is Required

Hilchos Kiddush HaChodesh 4:12

If the head of the Sanhedrin was away on a journey, the court may declare a leap year only on the condition that he will approve. If he returns and approves, the leap year takes effect; if he does not approve, it does not. A leap year may be only declared in Judea, which is considered the residence of God’s Presence as per Deuteronomy 12:5, “Seek out His dwelling.” If a leap year was declared in the Galilee, the declaration is nevertheless effective. A leap year is only declared during the day; if it was declared at night, the leap year does not take effect.

Hilchos Kiddush HaChodesh 4:13

The court has the authority to calculate and to establish leap years whenever they want, even several years in advance. Nevertheless, a given year can only be declared a leap year after Rosh Hashana, at which time a public announcement is made that it has been declared a leap year. Even this is only done in compelling circumstances; under normal circumstances, the announcement of a leap year is not made until Adar. The announcement is, “This is a leap year so next month is not Nisan, but rather Adar II.” If the court announces a leap year before Rosh Hashana, saying, “The coming year will be a leap year,” it does not make the new year a leap year.