1. A leap year is a year that includes an additional month.¹This month is added to juxtapose the lunar calendar upon which the months are based, with the solar calendar, which governs the years.The extra month that is added is always Adar,²The Mechilta (commenting on Exodus 12:2 states that just as when a month is made full the addition is made at the end of the month, so too, when a year is made full the addition is made at the end. (The year is considered as beginning in Nisan and ending in Adar.) and thus the year contains two Adarin: the first Adar and the second Adar.³Based on Hilchot Nedarim 10:6, it appears that the Rambam considers the first Adar to be the additional month of the leap year. The Tur and the Ramah (Orach Chayim 427:1) differ and consider the second Adar to be the additional month.

In practice, Purim is always celebrated in the second Adar (Hilchot Megillah 1:12). There is a difference of opinion with regard to whether to commemorate birthdays, yahrzeits, and the like that took place in Adar of an ordinary year in the first or the second Adar of a leap year. The accepted custom in the Ashkenazic community is to commemorate them in the first Adar of a leap year (Kitzur Shulchan Aruch 221:3).

Why is this month added? Because of the season of spring, so that Pesach will fall then, as [implied by Deuteronomy 16:1]: "Take heed the month of spring"⁴Based on this verse, Rav Sa'adiah Gaon considers the adjustment of the yearly calendar to be a separate mitzvah. The Rambam, by contrast, considers it one dimension of the mitzvah of establishing the calendar. [This command can be interpreted to mean, "Take heed] that this month falls in the spring season. Were the month [of Adar] not to be added [from time to time], there are times when Pesach would fall in the summer, and times [when it would fall] in the rainy season.

2. [An extra month is added,] making the year full, because of three factors: a) the vernal [spring] equinox;⁵In astronomical terms, the vernal equinox is defined as the entry of the sun into the constellation of Aries the ram (Chapter 9, Halachah 3). b) the ripening⁶We have translated the Hebrew word אביב as "ripening," as in Exodus 9:31. Because the agricultural cycle was so much an integral part of the calendar, the word אביב also means "spring" in Hebrew. [of the barley crop], and c) the blooming of the fruit trees.

What is implied? When the court calculates⁷The calculations that the court would consider are outlined in Chapter 9. and determines that the vernal equinox will fall on the sixteenth of Nisan or later, the year is made full. The month that would have been Nisan is made the second Adar, and thus Pesach will fall in the spring. This factor [alone] is sufficient for the court to make the year full;⁸The Ra'avad (in his gloss on Halachah 16), the Ramah and others take issue with the Rambam on this point, maintaining that even when Pesach falls before the vernal equinox, another factor is necessary for a leap year to be declared. other factors need not be considered.

3. Similarly, if the court sees that [the barley crop] has not ripened, but that it is late in sprouting, or that the fruit trees that usually bloom at the time of the Pesach holiday have not bloomed, these two factors are sufficient,⁹Both these factors are, however, necessary. Neither in their own right is sufficient. and the year is made full, even though the vernal equinox will fall before the sixteenth of Nisan.¹⁰Based on Sanhedrin 13a,b, the Ramah (cited in the gloss of the Kessef Mishneh on Halachah 15) notes that our Sages required that the festival of Sukkot occur after the autumnal equinox. If the vernal equinox falls on the fifteenth of Nisan, it is possible that the autumnal equinox will not take place until the twenty-first of Tishrei, six days after Sukkot begins.

Several different perspectives are offered to resolve this point. Among them: The Or Sameach maintains that the Rambam's text originally contained a reference to the autumnal equinox, and it was omitted by the later printers. Aruch HaShulchan, by contrast, maintains that, according to the Rambam, the entire discussion in Sanhedrin is not accepted as halachah. We are not at all concerned with the autumnal equinox; all that is significant is that Pesach fall after the vernal equinox.

[The reason the year is] made full [because of these factors] is so that there will be [an abundant quantity] of ripened [barley] accessible, so that the wave offering of the omer can be brought from it on the sixteenth of Nisan,¹¹See Leviticus 23:9-14; Hilchot Temidim UMusafim 7:3. and so that the fruits will bloom, as they always do in the spring.

4. There are three territories that are of consequence regarding the ripening [of the barley]: Judea, Transjordan, and the Galilee. If [the barley] ripened in two of these lands, but not in the third, the year is not made full.¹²The climates of these lands are different, and it is possible that the barley will have ripened in one land, but not in the others. If, however, [the barley] ripened in one of these lands, but not in the other two, the year is made full if the fruit trees have not bloomed.

These are the primary grounds for making the year full, so that the years will follow the solar calendar.¹³As opposed to the factors mentioned in the following halachot.

5. There are other factors for which the court makes [the year full] in the case of necessity.¹⁴I.e., these factors are not associated with the juxtaposition of the lunar and solar calendars, but rather related to the celebration of the pilgrimage festival of Pesach in a complete manner. Among them: that the roads are not suitable,¹⁵Because they were damaged by the rains. and it is impossible for the people to make the pilgrimage. [In such an instance,] the year is made full, [to allow time for] the rains to stop and the roads to be fixed.

That the bridges have been destroyed and there are rivers interrupting [the roads], and preventing the people [from continuing their journey]. The year is made full, so that the bridges can be fixed, lest the people endanger themselves and die.

That the ovens for the Paschal sacrifice were destroyed by the rains,¹⁶The ovens were earthenware, and could be damaged by substantial rains. and thus there will be no place for [the people] to roast their Paschal offerings. We therefore make the year full, so that the ovens can be built and can dry [in the sun].

That Jews from the diaspora who have left their homes have not arrived in Jerusalem. We make the year full, so that they will have the time to reach [Jerusalem].¹⁷The Jerusalem Talmud (Sanhedrin 1:2) states that an effort should be made to enable the entire Jewish people to celebrate the pilgrimage festivals in Jerusalem.

6. We do not, however, make the year full because of snow, nor because of a cold climate,¹⁸Rashi, Sanhedrin 12a, writes that these factors will make the people's journey to Jerusalem uncomfortable, but will not prevent them from making the journey. nor because of Jews from the diaspora who have not yet left their homes.

[Similarly, the year is not made full] because of ritual impurity - e.g., when most of the people or most of the priests are impure.¹⁹In his commentary on the tractate of Sanhedrin (one of the few tractates of the Gemara on which the Rambam wrote a commentary), the Rambam quotes Rav Hai Gaon as explaining that this instance refers to a situation in which the people were impure because of contact with a human corpse, and no ashes from the red heifer remained to purify them. One might think that the year should be made full to enable the priests enough time to offer a new red heifer and prepare ashes. Therefore, our Sages feel it necessary to explain that this measure is not taken, and in this instance the Paschal sacrifice should be offered by a priest in a state of ritual impurity. The year is not made full so that they will be able to purify themselves and offer [the Paschal sacrifice] in a state of ritual purity.²⁰On the one hand, an individual who is ritually impure may not offer the Paschal sacrifice at its appropriate time, but instead should offer it a month later, on Pesach Sheni. On the other hand, when the majority of the Jewish people, or the majority of the priests, are impure, the sacrifice should be offered in a state of ritual impurity. (See Hilchot Korban Pesach 7:1; Hilchot Bi'at HaMikdash 4:16.) Instead, they should offer [the sacrifice] while ritually impure. Nevertheless, if the year has been made full because of ritual impurity, it may be left full.

7. There are factors that, in and of themselves, are never sufficient cause to make the year full. They are, however, mentioned as contributing factors when a year must be made full so that [Pesach will fall after] the vernal equinox, because of [the barley that has not] ripened, or the fruit trees.

These factors are: That young goats or lambs have not been born, or are merely few in number, or that young doves have not [matured to the point where they can] fly.

We do not make the year full so that the goats and the lambs will be available for the Paschal sacrifices, and the doves will be available for the pilgrimage sacrifice,²¹Our Sages interpret Deuteronomy 16:16, "You shall not appear before God empty-handed," as obligating a person to bring an olah ("burnt") offering on the pilgrimage festivals. The Rambam maintains that doves could be brought for these offerings. (See Hilchot Chaggigah 1:1.) Other authorities differ, as explained in the commentaries on that halachah. or for those individuals²²E.g., a woman who gives birth (Leviticus 12:8 , zavim (Leviticus 15:14 , and zavot (Leviticus 15:29 . It was customary for people living far from Jerusalem to delay offering the sacrifices they were obligated to bring until the pilgrimage festivals. who are obligated to bring doves as a sacrifice. Nevertheless, these are mentioned as contributing factors [to make] the year [full].

8. What does mentioning them as contributing factors [to make] the year [full] imply? The court says: "This year must be made full because the equinox falls late, or because [the barley] has not ripened and the fruit trees have not bloomed,²³By mentioning both factors (the barley and the fruit trees), the Rambam indicates that he does not follow the perspective suggested by Rashi (Sanhedrin 11a), which states that the lack of lambs or doves coupled with either a delay in the ripening of the barley or the blooming of the fruit trees is sufficient cause to make the year full. and also because the young goats are small and the doves are frail."

9. The year can be made full only by [judges] who were invited [to participate in the deliberations].²⁴See Sanhedrin 11a, which relates that Rabban Gamliel once invited seven members of the Sanhedrin to participate in the deliberations regarding whether or not to make a year full. He requested that they meet him in the loft of the court early the following morning. When an additional member of the court came, Rabban Gamliel protested and taught the Sages this halachah. What is implied? The head of the High Court²⁵For a leap year can be declared only by the High Court, or by a court deputized by the High Court (Chapter 5, Halachah 1). tells [several] members of the court, "Be present at a particular place, where we will make calculations and decide whether or not it is necessary to make the year full" It is only those who were invited who [have the authority to] make [the year] full.

How many [judges participate in the deliberations whether] to declare a leap year? We begin with three judges from the High Court who have received semichah. Should two [of these judges] say, "There is no need to sit to decide whether or not [the year] should be made full" [their opinion is accepted]. [Although] one [judge] says that they should continue their deliberations, his statements are of no consequence.

If two [of these judges] say, "There is a need to sit [further] to decide whether or not it is necessary to make [the year] full" and the other [judge] says that they should not continue their deliberations, we add two of the judges who had been invited previously, and the discussion of the matter [is continued].

10. Should two [judges] say that it is necessary to make [the year] full, and three say that there is no necessity, [the opinion of] the two is of no consequence. If three [judges] say that it is necessary to make [the year] full, and two say that there is no necessity, two more [judges] who were invited are added to the court, and the subject is debated.

These seven [judges should] arrive at a conclusion. If they all agree to make the year full, or not to make the year full, their decision is followed. If there is a difference of opinion among them, we follow the majority, whether to make the year full, or not to make the year full.

It is necessary that the head of the High Court - i.e., the one who presides over the seventy-one [judges of the Sanhedrin] - be one of these seven. If [the three original judges] conclude²⁶When there are fewer than seven judges in the court, a leap year is instituted only when the decision to do so is unanimous. Only when the court is expanded to include seven judges is a majority ruling accepted as binding (Rabbenu Chananel, Sanhedrin 10b). that it is necessary for the year to be made full, it should be made full, provided the nasi²⁷I.e., the head of the court. is among the three, or consents [to their ruling].

Concerning the institution of a leap year, the opinions of the lesser judges should be offered first.²⁸Lest the lesser judges be intimidated after hearing the decision of the head of the court, and refrain from expressing their own opinion. Concerning the sanctification of the new month, we begin from the head of the court.²⁹For the matter is more of a formality; the head of the court merely pronounces the month as sanctified.

11. Neither a king³⁰Based on this ruling, Rabbi Akiva Eiger questions why King Chizkiyah was able to institute a leap year, as related in Pesachim 4:10. nor a High Priest should be [included in the group entrusted with deciding] whether or not to institute a leap year. A king [should not be included, lest he be influenced] by consideration for his soldiers and his wars.³¹Rashi (Sanhedrin 18b) states that the king would pay his soldiers a yearly salary, and therefore, by instituting an extra month, he would gain.

The B'nei Binyamin explains that there is also a reason for a king to desire to refrain from instituting an extra month. Bridegrooms, those who have built new homes, and those who have planted vineyards are freed from army service for a year. If a leap year is instituted, they benefit. Therefore, if a sizable portion of the population fell into these categories, and men were required for the army, it would be preferable for the king not to institute a leap year.

A High Priest should not be included because of the cold - i.e., he may choose not to institute a leap year so that Tishrei will not fall in the winter, and he would [thereby not] have to immerse himself five times on Yom Kippur [in such weather].

12. If the head of the High Court, the nasi, was on a distant journey, [the court] may institute a leap year only with the proviso that the nasi will consent. If the nasi comes and consents, the year is full. If he does not consent, it is not full.

A leap year may be instituted only in the territory of Judea, for the resting place of the Divine Presence³²I.e., the Temple in Jerusalem. Curiously, however, it does not appear that the Rambam requires the proceedings to be carried out in the Temple, or even in Jerusalem. is there, as [implied by Deuteronomy 12:5]: "And you shall seek out his dwelling" If a leap year is instituted in the Galilee, the year remains full.

A year should be made full only during the day.³³Sanhedrin 11b states that there is an equation between the institution of a leap year and the sanctification of the new moon. As mentioned in Chapter 2, Halachah 8, the new moon can be sanctified only during the day.

Based on the equation between these two practices, the Minchat Chinuch (Mitzvah 4) questions the law mentioned previously: Why may the moon be sanctified throughout Eretz Yisrael (Chapter 1, Halachah 8) if a leap year may be instituted only in the territory of Judea? If it is made full during the night, it is not full.

13. The court has the authority to calculate, institute, and decide which year(s) shall be full whenever it desires, even several years in advance.³⁴Sanhedrin 12a relates that once, when Rabbi Akiva was imprisoned by the Romans, he instituted three leap years for the future. Nevertheless, a particular year is not declared a full year until after Rosh Hashanah, at which time a public statement [can be] made [to the effect that] the year has been made full.³⁵Shorshei HaYam cites the fact that the year can be declared a leap year well in advance, as support for the Rambam's thesis (Halachah 2) that the fact that Pesach would be celebrated before the vernal equinox is, by itself, sufficient cause to declare a leap year. At the beginning of the year, it is impossible to know the state of the barley harvest, or the fruit trees.

[A leap year is announced at such an early date] only in a pressing situation.³⁶Rashi (Sanhedrin, ibid.) relates that this refers to a situation when it was feared that the Romans would prevent the leap year from being instituted if the court waited for the usual time.

Note the Minchat Chinuch (Mitzvah 4), which explains that an early declaration should be made only in a pressing situation. The court may, however, calculate months and even years in advance, even in cases where the situation is not pressing. If the situation is not pressing, the announcement that a leap year has been instituted is not made until the month of Adar. [At that time, the court announces,] "This year is a leap year, and the following month is not Nisan, but rather the second Adar" If a court announces before Rosh HaShanah, "The year to come will be a leap year" this announcement does not make the year a leap year.

14. If the thirtieth day of Adar arrived without the year having been declared a leap year, it should never be made a leap year.³⁷I.e., although, as the Rambam continues, if they instituted a leap year on this date their ruling would be binding, at the outset they should not take such a step.

Pesachim 4:10 relates that declaring a leap year on this date was one of the three acts performed by King Chizkiyah that did not find favor in the eyes of the Sages. For that date is fit to be Rosh Chodesh Nisan, and once Nisan begins without the year having been declared a leap year, [the court] no longer has that option. If, however, they declared a leap year on the thirtieth of Adar, their ruling is binding.

If witnesses came after the leap year had been declared and testified regarding [the sighting of] the moon, the court sanctifies the new month on the thirtieth day, and makes it the Rosh Chodesh of the second Adar.³⁸Retroactively, it appears that the thirtieth day was fit to be Rosh Chodesh Nisan, and therefore the institution of the leap year would not have been effective. Nevertheless, since in actual fact, the declaration of the leap year preceded the sanctification of the new month, it is effective. If they had sanctified the new month on the thirtieth day before they declared a leap year, they would not have been able to declare the leap year. For a leap year may not be declared in Nisan.

15. A leap year may not be declared in a year of famine³⁹Sanhedrin 12a credits Elisha the prophet with the institution of this prohibition. when everyone is hurrying to the granaries to partake [of the new year's harvest] and derive vitality. [In such a situation,] it is impossible to prolong the time when the prohibition against eating from the new harvest [is in effect].⁴⁰The prohibition of chadash prevents one from partaking of grain from the new harvest until the offering of the omer of barley on the sixteenth of Nisan (Hilchot Ma'achalot Asurot 10:2-5). When the previous year has been plagued with famine, it is undesirable to keep this prohibition in effect any longer than necessary.

We do not declare the Sabbatical year⁴¹The Rambam follows the opinion in Sanhedrin (loc. cit.), which forbids instituting a leap year only in the Sabbatical year. Another opinion forbids instituting a leap year in the year following the Sabbatical year. a leap year, because everyone is entitled to take the crops that grow on their own.⁴²Our translation follows the commentary of the Perush, which explains that according to the Torah, all agricultural labor is forbidden in the Sabbatical year. It is, nevertheless, permitted to take crops that grow from seeds strewn by the wind or that grow from other causes that did not result from conscious human labor. Although our Sages forbade benefitting from such crops for personal use, it was from these crops that the grain used for the omer offering and the two loaves of bread were harvested.

The Sages forbade using these crops for personal use. Nevertheless, since the prohibition did not originate in the Torah, our Sages feared that it would not be observed by the common people and the crops would not remain for these sacrifices.

Significantly, Rashi and others offer a second rationale for this practice, that our Sages did not want to prolong a year when it was forbidden to do agricultural work. Therefore, grain will not be available to offer the omer [of barley] and the two loaves of bread [offered on Shavuot].⁴³See Leviticus 23:17. As the verse states, this offering and the omer must be from the harvest of the new year. It was customary to make the year preceding the Sabbatical year a leap year.⁴⁴So that the farmers would have an extra month to work the land and gather its crops (Rashi, Sanhedrin, loc. cit.).

16. It appears to me⁴⁵This expression indicates a ruling that the Rambam derives from his own logic without an explicit source in the works of our Sages. The Or Sameach cites a passage (Sanhedrin 26a), which appears to indicate that it is impossible to declare a Sabbatical year a leap year. There are, however, other interpretations of that passage. (See Tosafot, loc. cit..) that our Sages' statement that a leap year should not be declared in a year of famine and in the Sabbatical year means that a leap year should not be declared because of the condition of the roads or the bridges, or because of factors of this nature. If, however, it is appropriate to declare a leap year because [Pesach will fall before] the vernal equinox, because [the barley has not] ripened, or because the fruit trees [have not bloomed], a leap year is declared always.⁴⁶It appears that the Rambam's logic is that since according to the Torah, it is necessary to declare a leap year under such circumstances, the leap year should be declared. There is no obligation from the Torah to declare a leap year, because of problems with the roads or because of the other circumstances mentioned in Halachah 5. The Sages prescribed ordaining a leap year in these circumstances out of consideration for the people. In a Sabbatical year or a year of famine, the considerations mentioned in the previous halachah override those that would ordinarily require the year to be declared a leap year.

Significantly, the Ra'avad, the Ramah, and others do not accept the distinction made by the Rambam, and maintain that a Sabbatical year and a year of famine should never be declared leap years.

17. When the court institutes a leap year, they write a letter to all [the people in] distant places, notifying them that a leap year has been instituted, and the reason for which it was instituted.

These letters were written in the name of the nasi.⁴⁷The Rambam's statement is based on the narrative in Sanhedrin 11b, which relates that Rabban Gamliel sent letters to Jews throughout the diaspora notifying them of the declaration of a leap year. They would say, "Let it be known that I and my colleagues have agreed to add to this year this many days" - for it was possible for them to declare a month of twenty-nine days or a month of thirty days.

[The intent is that] the court had the option of notifying the people in the outlying areas that the month would [probably] be either full or lacking.⁴⁸Since through calculations, it is possible to know whether or not it is likely for the moon to be sighted on the thirtieth night, the court would notify the people in the outlying areas accordingly. This notification would, however, be conditional on the actual sighting of the moon. [In fact, however,] the determination of whether the month is full or lacking is dependent on the sighting of the moon.