Halakhic Issues Raised by the Leap Year

  • Rav Binyamin Tabory


The Jewish calendar year is based on the movements of both the moon and the sun. Months are naturally measured by the cycle of the moon, while years and seasons follow the sun. Whereas a purely solar calendar must arbitrarily chop up a 365-day year into twelve pieces in order to create months, and a purely lunar calendar must arbitrarily pick some quantity of months to measure years, the Jewish calendar balances lunar months with solar years.

This fulfills the biblical command to ensure that Pesach always comes out in the spring: "Keep the holiday of the spring." If a purely lunar calendar were followed, the season within which Pesach falls would gradually drift away from spring, moving from season to season about every nine years (a twelve lunar-month year falls eleven days short of a 365-day solar year). Periodically adding an extra month to the year aligns the lunar calendar with the solar.

The first Adar is this extra month. When the months were sanctified monthly (kiddush ha-chodesh) by the Sanhedrin, the Sages would convene before Nisan and decide (based on seasonal indicators) whether to add a month to the year. In a permanent calendar system (whose foundations were set up by the amora Hillel the Third - 359 CE), an extra Adar is added in seven out of every nineteen years.

In years with two Adars, a number of questions naturally arise. In which of the two Adars is Purim celebrated? When does someone born in Adar become a bar mitzva? When is the yahrzeit of one who passed away in Adar commemorated? Does the technical term "year" (in contracts, vows, etc.) include both Adars or does it finish after twelve months?


The mishna (Megilla 6b) deals directly with the laws of Purim during a leap year:

"If the megilla was read in Adar I and then the year was declared a leap year (i.e., another month was added), it is read again in Adar II. The only difference between Adar I and Adar II is with regard to reading the megilla and giving presents to the poor (matanot la-evyonim)."

The gemara quotes a dispute among the tannaim about whether the obligation to read the megilla can be fulfilled in Adar I or only in Adar II. If the latter is true, then the megilla must be read in Adar II even if one already read it in Adar I.

The mishna refers to a case where a leap year was declared by the Sanhedrin after the megilla had already been read in the first Adar. What is the halakha now that we work with a fixed calendar? Both tannaim in the gemara agree that one who reads the megilla in Adar II has fulfilled his obligation. The whole discussion there is whether one who has already read it in Adar I has fulfilled his obligation post facto. Therefore, in a situation where we have a choice between the two Adars, it is clear that megilla reading and matanot la-evyonim should be done in Adar II.

The dispute between the tanna'im about when to read the megilla when there are two Adars stems from how they each understand the verse "[to keep the fourteenth ... and the fifteenth ...] every year" (Esther 9:21). The basic implication of this verse is that a year that has two Adars should be similar (based on "every year") to the rest of the years. The tanna'im argue about HOW they should be similar. One tanna understands that just like every year the megilla is read in the month that immediately follows Shevat, so too in a leap year it should be read in Adar I. The other holds that just like every year the megilla is read in the month immediately preceding Nissan, so it should be read during a leap year.

The gemara then proceeds to put forward a further rationale for each of the two opinions. It should be read in Adar I, they say, because a mitzva should be done at the first possible opportunity. According to the other opinion, Purim should be juxtaposed, as much as possible, to Pesach, based on the principle that the two holidays of redemption should be adjacent to each other.

If there is already a way of supporting each opinion based on halakhic principles, why must the gemara also bring the proofs from the verse? Apparently, without the verse "every year," we would have thought that we are obligated to read the megilla TWICE during a leap year, to fulfill both halakhic principles. Based on the verse, however, we only read once; the question which the gemara then answers is: which month?

What about the prohibition against fasting (ta'anit) and eulogies (hesped) on Purim? What about the mitzva to be joyous (simcha) on Purim? Do these also apply only to Adar II, or do they apply to Purim in Adar I (what we call Purim Katan) as well?

Three opinions appear in the rishonim about the status of Purim Katan:

  1. The Tosafot say that there is a prohibition against eulogies, but no mitzva to be joyous.
  2. The Rosh says that the mitzva of joy and the prohibition against eulogies are linked, and both do NOT apply to Adar I.
  3. The Ran takes the opposite approach. He agrees with the Rosh that simcha and hesped go hand in hand, however, he holds that both DO apply in Adar I.

By examining other laws which are affected by the leap year, we will gain a better understanding of its nature and consequently the dispute regarding Purim Katan will become clearer too.

[For more on the effect of the leap year on the laws of Purim, see Rav Yair Kahn's VBM article:



The gemara (Nedarim 63a) deals with one who vowed in Adar not to drink wine "for a full year." If the year was subsequently made into a leap year, must he keep his vow for only twelve months (a "year" = 12 months, ending in Adar I), or must he keep a full thirteen months (a "year" includes the leap month) ending in Adar II? The mishna says that it depends on the terminology he uses in his vow. The term "year" includes the leap month; "until Rosh Chodesh" means until Rosh Chodesh of the FIRST Adar, and "until the end of Adar" implies until the end of the SECOND Adar.

The gemara also asks about one who, in formulating his vow, says "Adar," yet does not specify which Adar he is referring to. The same passage deals with a parallel issue in the writing of contracts - does "Adar" (unspecified) refer to the first or the second Adar?

The gemara concludes by distinguishing between a case when the person using the word Adar knows about the leap year and when he does not. People who know about the leap year refer to Adar II when they use the word Adar without specifying; those who do not know about the leap year are referring to the first appearance of Adar, namely - Adar I.

To understand this, it is crucial to differentiate between two separate issues:

1. which Adar is, objectively, the real Adar of the calendar;

2. what people mean when they use the word "Adar" without specifying.

Only this second question is the focus of the gemara in Nedarim. The content of a vow is totally dependent on what a person's intention is. This is the foundation of the Talmud's axiom to follow the commonly understood meaning of human speech (and not necessarily a word's biblical or halakhic meaning) when determining what a person's vow means. The rules of vows and contracts can therefore be viewed independently of some of the other issues that we will discuss.


In discussing rental for a year during a leap year, the mishna (Bava Metzia 102) seems also to be based on subjective criteria: when a rental agreement states "a year," do the two parties intend to include the second Adar or not?

Another issue, the sale of homes in walled cities, might shed light on whether the Halakha objectively defines a year to include the leap month or not. One who sells a home in a walled city in Israel has one year within which he can force the buyer to sell it back to him at the same price. The mishna (Arakhin 31a) rules that in a leap year, the seller has THIRTEEN months to do this. The gemara bases this on the Torah's expression, "a complete year" (shana temima - Vayikra 25:30).

This does not necessarily solve our problem. Perhaps a year in Halakha does not, in general, include the leap month, but the special expression, "temima," indicates that the rule of sales in walled cities is unique. Consequently, the Rashba (Nedarim 63a) infers that the Torah's year in general is only twelve months, even in a leap year. The Ran explores the possibility that the Torah's year during a leap year is indeed thirteen months long, and offers an alternative explanation for the special need to indicate this in the law of walled cities. (See his comments on Nedarim 63a.)


Several rishonim discuss how the leap year affects the date of a child's bar mitzva. There are three possible situations which need to be examined:

  1. the child is born in Adar of a regular year, and he becomes bar mitzva in a leap year;
  2. he is born in a leap year, and becomes bar mitzva in a normal year;
  3. both the year he is born in and the one within which he becomes bar mitzva are leap years.

1. The Shulchan Arukh (OC 55:10) states that the leap year is considered thirteen months long with regard to bar mitzva. The Rema (OC 55:11) quotes the Mahari Mintz, who explicitly rules that a child born in Adar of a regular year becomes bar mitzva in Adar II of the leap year. As a prooftext, the rishonim quote the Yerushalmi at the end of Ketubot 1:2, which implies that a young girl's basic physical maturity (after three years old) will naturally modify itself in order to fit in with the leap year. The gemara's solution to the conflict between the physical and the calendar reality is a supernatural one: the physical reality models the calendar one. The same thing must be true of bar mitzva, for thirteen years old is the default age for a boy's maturation.

The Peri Chadash quotes a dissenting opinion, that in Adar I the boy physically matures. Some, in order to account for this opinion, make sure that a child in such a situation already keeps mitzvot a month earlier than his real bar mitzva. (See Responsa Beit Shlomo, Even Ha'ezer # 56.)

2. If a child is born in Adar II and his bar mitzva takes place in a year with only one Adar, he becomes bar mitzva in Adar and not Nisan. A curious outcome of this halakha (Shulchan Arukh OC 55:11) is that a child who is "younger" can become bar mitzva before an older one. A child born on 6 Adar II will become bar mitzva earlier than one born on 7 Adar I of that same year, since in their bar mitzva year there is only one Adar. (Arakhin 31b contains a similar discussion with regard to redeeming houses in walled cities.)

3. Where both the year of a child's birth and the year of his bar mitzva have two Adars, we would expect a child to become bar mitzva in the same Adar he was born in. Even if Adar I is considered a second Shevat, it would be inconsistent not to relate to both Adar I's the same way - either both are Shevats or both Adars. This is the opinion of most acharonim, except for the Magen Avraham. According to him, no matter which Adar the child was born in, he becomes bar mitzva in Adar II.


A similar set of problems arises concerning the laws of mourning. The determination of when a year of mourning for parents ends is unaffected by how we view the two months of Adar. Mourning for parents, in principle, lasts twelve months, not a year. The two Adars must count as two months, no matter what. (See Rosh, Mo'ed Katan 3:50, and Shulchan Arukh YD 391.)

However, determining the yahrzeit (yearly commemoration of a relative's passing away) requires fixing a date, a day within a particular month every year. If someone passed away in Adar, it is crucial to know in which Adar to commemorate the yahrzeit. The authorities differ about how to deal with this dilemma.

The Shulchan Arukh (OC 568:7) rules that the yahrzeit takes place in the second Adar, whereas the Rema, based on the Maharil, argues that the yahrzeit should take place in Adar I. The Gra, in his commentary to the Shulchan Arukh, takes a stringent approach and rules that one should observe a yahrzeit in both Adars. In order to understand the basis of their dispute, it is necessary to better understand what determines when the yearly yahrzeit commemoration takes place.

Several approaches present themselves:

1. The yahrzeit is fixed on the date that the twelve months of mourning end. The Chatam Sofer (Responsa OC 14) rejects this possibility, since the yahrzeit of someone who died in Shevat of a leap year would then always be commemorated in Tevet. The Chatam Sofer explains that the discussion among the poskim was limited to the question of the two Adars in a leap year.

2. The yahrzeit might be determined by the day of passing away. During leap years, Adar II is always considered in place of the normal Adar; therefore, the yahrzeit should be commemorated in Adar II.

3. The yahrzeit is determined by the day of passing away, but the date when the twelve-month mourning period ends is commemorated as the yahrzeit. Because the mourning ends in Adar I, the yahrzeit is commemorated in Adar I. Many acharonim understood these last two options as the rationale behind the two approaches that the poskim raise.

4. A fourth approach, taken by the Gra, fits in with the simple meaning of what a yahrzeit is. The concept behind the yahrzeit is that on a certain DATE in the calendar one keeps certain customs. In order to determine when an Adar yahrzeit takes place, one must determine when Adar is. Based on a passage in Massekhet Megilla, it seems that both Adar I and Adar II are legitimately considered Adar. If one would ask when Adar 7th falls out, the correct calendar answer is twice - once on the 7th of Adar I, and once on the 7th of Adar II. The gemara needs a special derivation from the expression "in every year" to teach us that Purim is unique and to limit the Purim celebration to only one of the Adars. Nevertheless, the gemara assumes that both Adars are considered legitimately to be Adar. The Gra (OC 368) therefore holds that an Adar yahrzeit should be commemorated twice in a leap year, once in Adar I and once in Adar II.

The Chatam Sofer's question (see 1 above) is now easily solved. The yahrzeit of someone who passes away in Shevat of a leap year will obviously occur in Shevat every year. That is the calendar date to be commemorated. Likewise, the yahrzeit of one who passes away in Adar will also always fall out in Adar - and both Adars are considered Adar on the calendar. [There is still room to differentiate between different types of yahrzeit customs; see Mishna Berura, OC 368.]

This question might be dependent on the nature of yahrzeits in general. See the Chatam Sofer's comments below regarding days commemorating miracles.


We will mention briefly five additional halakhic issues that arise in leap years.

A. From the verse, "He should be free to stay at home for one year" (Devarim 24:5), we learn that there is a mitzva for a man to make his wife happy during their first year of marriage. (In his commentary to this verse, the Netziv views this as a mitzva incumbent on army officers not to draft newlywed men, but not as a mitzva on the husband himself.) How long does this mitzva last in a leap year - twelve months or thirteen? The Aderet, Rav Eliahu David Rabinowitz Teomim (quoted in an appendix to the Minchat Chinukh), raised this question.

B. Some are accustomed to treat the seventh of Adar, the yahrzeit of Moshe Rabbeinu, as a minor festival. Chevrot kadishot, Jewish burial societies, have their annual dinner after the seventh of Adar. Some have a custom to fast on this day. Rav Ovadia Yosef (Yechaveh Da'at 1:3) discusses this issue and rules that it should be commemorated in Adar II. The Magen Avraham (OC 380:18) and other acharonim rule that it should be observed in Adar I. (It is not clear whether the year Moshe passed away was a leap year or not.)

C. Celebrating the day of a personal miracle: When should this celebration, tantamount to a mini-Purim, take place in a leap year? The Mishna Berura (OC 686:8) rules that it should take place in Adar II.

Rav Shaul Frimer (Or Hamizrach #110-111, p. 322) points out that in the source of this ruling, the Chatam Sofer (Responsa OC #163) distinguishes between different types of customs. If the day of the miracle is commemorated as a fast day, it should be observed in Adar II, based on the talmudic guideline to push off fast days to a later date (for example, if the normal date comes out on Shabbat). If, on the other hand, the day of the miracle is celebrated as a holiday, then

"He need only trouble himself once (and Adar II is preferred in this over Adar I, because it brings his personal celebration and redemption closer to the other holiday of redemption, Pesach). Matters that do not involve trouble, such as refraining from something, must be observed in both Adars."

D. If someone has resided on a piece of land for three years, he thereby stakes a claim to the land (chezkat shalosh shanim). The Ritva (Bava Batra 28a) rules:

"The three years of chazaka do not follow the calendar date, from Tishrei to Tishrei. Rather, one begins to count twelve months from the moment he takes hold of the land, and continues to count until thirty-six months elapse."

The Pitchei Teshuva (CM 141) relates to this issue and leaves it unresolved.

E. Parashat Zakhor, read the Shabbat before Purim, is, according to many poskim, a biblical mitzva. They understand that the commands to "remember" and "not forget" Amalek require us to read the portion in the Torah about Amalek once a year. What defines a "year" with regard to this mitzva? If a year is defined as being twelve months long, then our custom to read Parashat Zakhor on the Shabbat before Purim is problematic, since more than twelve months may elapse between readings. Since the goal of the mitzva of Parashat Zakhor is to remind us about Amalek, twelve months is particularly appropriate. In the laws of mourning, this is considered the time after which one begins to forget one's loss. It is fitting that a yearly reminder should come up at twelve-month intervals.

Within our system of reading the Torah, we can solve the problem by intending to fulfill the mitzva of Zakhor on the Shabbat when the portion of Ki Teitzei is read (roughly six months after Shabbat Zakhor). However, what would those who followed the old custom of spreading the Torah reading over three years do? The Chatam Sofer (Even Haezer #119) raises an unconventional possibility that in a leap year, the amount of time for forgetting is thirteen months! (See Mo'adim U-zemanim 2:166 for a discussion of this issue.)


How to treat the leap year in a particular realm of halakha is dependent on what the crucial units of time in that realm are. When a number of MONTHS must be counted - twelve months of mourning, or, according to the Ritva, the thirty-six months of chazaka - it is irrelevant whether the year is a leap year or not. One simply counts the months, no matter what their names are.

On the other hand, when a YEAR must be counted, the leap month is included. The year within which a seller has a chance to buy back the property he sold in a walled city includes the leap month. A child reaches the age of bar mitzva when he has COMPLETED thirteen YEARS, and must therefore include the leap month of his thirteenth year, according to most poskim.

Sometimes, as in a yahrzeit, a DATE is commemorated. One must determine when dates that come out in Adar fall out in a leap year. According to the Gra, since both Adars are really considered Adar as far as the date on the calendar is considered (Purim has been specially excluded and takes place only once), one observes an Adar yahrzeit in both Adars. When writing the date in a legal document, one must take care to differentiate between Adar I and Adar II (see Nedarim 63a and compare to Yerushalmi Megilla 1:5).

In some realms, a year is defined SUBJECTIVELY. Whether a vow that lasts a year includes the leap month or not depends on what people intend when they refer to a year. Although both dates are considered Adar, only one of them is relevant. According to the Chatam Sofer, the Adar in which one celebrates a personal Purim is dependent on how one understands the nature of the day. The same might be true of the seventh of Adar and yahrzeit.

Our original discussion, as to whether there is a mitzva of joy and a prohibition against fasting and eulogies on Purim Katan (the fourteenth of Adar I), takes on a new light now. When the verse limits Purim to one date, Adar II and not Adar I, it would seem that the fourteenth of Adar I should be viewed as a totally non-Purim day.

The Rosh, in fact, holds that there is no obligation of happiness in Adar I. His comment that Adar I is like Shevat does not necessarily mean that he argues with the approach we have been following, viewing both Adars as truly Adar. He might only be calling it Shevat with regard to Purim, once the verse has taught us when to celebrate Purim.

Tosafot distinguish between Megillat Esther, excluded from Adar I by the verse, and the prohibition against fasting, stemming from Megillat Ta'anit, and dependent on the date. (See Rav Kahn's aforementioned shiur about the status of Adar I.) Therefore, the Megilla is read and the mitzva to be joyous applies only in Adar II, yet it is still forbidden to fast on the fourteenth of Adar I. The Ran also seems to believe that the date "the fourteenth of Adar" appears twice on the calendar, and likewise distinguishes between Megilla on the one hand, which we read only once, and se'udat Purim and the prohibition against fasting, on the other hand, which are linked to the date. Since the date occurs twice, these mitzvot apply twice.

Rav Yair Kahn pointed out in conversation that Rav Aharon Turtchin (in his Kuntres Chanuka U-megilla) explains the Ran differently. He sees the mitzva of se'udat Purim, the feast of Purim, as also dependent on Megillat Ta'anit (instead of the date 14 Adar, as we presented it), and that is why it applies in Adar I too. Whether one says "Al Ha-nisim" in the se'udat Purim Katan might be a practical difference between the two approaches.

The Shulchan Arukh quotes the Tosafot and then adds the Rosh's opinion. The Rema adds that the custom is to follow the Tosafot (prohibiting fasting on 14 Adar I, but not obligating a feast) and, as an additional opinion ("yesh omrim"), quotes those who obligate feasting on Purim Katan also. In the last subsection of Orach Chayim, he concludes:

"Nevertheless one should somehow add to one's meal in order to follow the stringent opinions, 'and the good heart has constant festivity.'"


Translated and adapted by Rav Eliezer Kwass