During the times of the Bet Ha’mikdash, the nation’s officials would announce to the people during the month of Adar that they must send in their Mahasit Ha’shekel, the mandatory annual donation to the Bet Ha’mikdash. The "fiscal year" of the Bet Ha’mikdash began in Nissan, and therefore, starting with the onset of Adar – the month before Nissan – preparations for the next year’s budget began, with the solicitation of the Mahasit Ha’shekel.
Unfortunately, due to our unworthiness, we do not have a Bet Ha’mikdash, and we are therefore unable to fulfill this Misva of Mahasit Ha’shekel during the month of Adar. However, as the Mishna Berura (Rabbi Yisrael Meir Kagan of Radin, 1839-1933) cites (in Siman 685) from the Lebush, we commemorate this donation through the reading of "Parashat Shekalim" on the Shabbat that precedes Rosh Hodesh Adar (which we call "Shabbat Shekalim"). By reading about this Misva of Mahasit Ha’shekel, we are considered, on some level, as though we actually fulfill this Misva. This resembles the concept of "U’neshalema Farim Sefatenu," which means that we read and study the verses relating to the sacrifices and are thereby considered to have actually offered the sacrifices. Similarly, we read about the Mahasit Ha’shekel and are thus considered to have fulfilled this Misva.
There are a number of Rishonim (Medieval Halachic scholars) who maintained that the annual reading of Parashat Shekalim constitutes a Torah obligation. This is the implication of Tosafot (Medieval French and German scholars), in Masechet Berachot (13a). Halacha does not, however, follow this view, and we maintain that this annual reading is required on the level of Mi’de’rabbanan (Rabbinic enactment).
Hacham Ovadia Yosef ruled that women are not included in the obligation of Parashat Shekalim. Since this Misva applies only on specific occasions, it has the status of "Misva She’ha’zman Gerama" (a time-bound Misva), from which women are generally exempt. Therefore, strictly speaking, there is no obligation for a woman to attend the synagogue to hear the reading of Parashat Shekalim.
It is customary to bring two Torah scrolls from the ark in the synagogue on Shabbat Shekalim. From the first, we read that week’s Parasha, and we use the second for the reading of Parashat Shekalim for the Maftir. Hacham Ovadia Yosef writes that if the first Torah scroll is found to be Pasul (invalid for use) during the reading of the weekly Parasha, it is preferable to continue the reading from the second scroll, which had been taken from the ark for Parashat Shekalim, rather than take a third scroll from the ark. Normally, in a situation where a Torah scroll is found to be invalid, we leave it on the Teba (table) as a sign of respect and bring a new Torah from the ark. On Shabbat Shekalim, however, the two readings – the weekly Parasha and the special reading of Shekalim – are in close proximity to one another. For example, this year (5771), Shabbat Shekalim occurs on the Shabbat when we read Parashat Pekudeh, which is only two Parashiyot after Parashat Ki-Tisa, where the section of Shekalim appears. Therefore, it would not cause undue inconvenience to the congregation to roll the Sefer Torah from Parashat Shekalim to the weekly Parasha, and then back to Parashat Shekalim for Maftir. Hacham Ovadia maintains that this is preferable to removing a third Sefer Torah from the ark, given that there is little or no inconvenience entailed.
Summary: There is a Misva for a congregation to read the special section of Parashat Shekalim on the Shabbat preceding Rosh Hodesh Adar. Women are exempt from this obligation. We take two Torah scrolls from the ark – the first for the reading of the weekly Parasha, and the second for the special reading of Shekalim. If the first Torah scroll is found to be invalid, the Torah scroll that was taken for Shekalim should be used for the weekly reading and then rolled back to the section of Shekalim. This is preferable to taking a third Torah scroll from the ark.
