There is a Torah command upon each and every Jew to write a Sefer Torah (or to hire somebody to write one for him). The Sages inferred this Misva from the verse in the Book of Debarim (31:19), "And now, write for yourselves this Shira [literally, ‘song’]." Even if a person inherited a Torah scroll from his father, he is nevertheless obligated to write his own Sefer Torah.
One does not recite a Beracha over this Misva. If somebody hires a Sofer (scribe) to write a Sefer Torah for him, he does not recite a Beracha "Al Misvat Ketibat Sefer Torah" when the Sofer completes the Torah. Likewise, one does not recite the Beracha of "Shehehiyanu" on the completion of a new Sefer Torah. Nevertheless, it is customary at a dedication ceremony for a new Sefer Torah that the donor who funded the project wears a new suit and recites "Shehehiyanu" over the suit, having in mind for the Beracha to apply as well to the new Torah scroll.
The work "Me’il Sedaka" rules that one may count the money expended on writing a Sefer Torah toward his "Ma’aser Kesafim" (the ten percent of his income given to charity). This ruling, at first glance, seems surprising, given that writing a Sefer Torah constitutes a Halachic obligation, and obligatory expenditures for Misvot generally do not count toward "Ma’aser Kesafim." The "Me’il Sedaka," however, distinguishes between the Misva of writing a Sefer Torah and other Misvot in this regard, and allows using money of "Ma’aser Kesafim" for writing a Sefer Torah, and this ruling is cited as Halacha in the work Yalkut Yosef.
If a group of people get together to share in the cost of writing a Torah scroll, do they fulfill their obligation to write a Sefer Torah?
Hacham Ovadia Yosef, in one of his responsa, cites many authorities who rule that one does not fulfill the Misva if he joins with partners in sponsoring the writing of a Sefer Torah. As for the final Halacha, however, Hacham Ovadia rules leniently in this regard, based upon the ruling of the Hesed Le’Abraham. The Hesed Le’Abraham notes that according to the Rosh (Rabbenu Asher Ben Yehiel, 1250-1327), the Misva is to write a Sefer Torah from which one will study. (For this reason, the Rosh held that nowadays, we fulfill the Misva through the purchase of Torah study texts, such as Humashim, Gemariyot, works of Halacha, and so on.) When a group of people collectively sponsor a Sefer Torah, the "Hesed Le’Abraham" writes, it is implicitly understood that when any member of the group is called to read from the Torah, the Torah belongs to him at that moment. Thus, since they have each written a Torah from which they can learn, they each fulfill the Misva. Although it is certainly preferable to sponsor a Sefer Torah individually, people who join together as partners in sponsoring a Sefer Torah fulfill the Misva. This is also the ruling of Rav Yitzchak Elchanan Spektor of Kovno (Lithuania, 1816-1895).
Summary: There is a Misva to write (or commission the writing of) a Sefer Torah, and one may use money from "Ma’aser Kesafim" for this purpose. This Misva can be fulfilled by getting together with other people to cosponsor the project.
