In response to the miracles performed for Am Yisroel during the events of Purim, Mordechai and Esther introduced the obligation of Matanos l’Evyonim, giving gifts to the poor on Purim. Our sages, based on the plural of “gifts” in the Megillah, established the mitzvah of giving a gift to at least two poor people on Purim (Megillah 7b, Be’er Heiteiv 694:1).
Concerning this mitzvah, the Rambam says: “It is better to provide more gifts to the poor than to have a costlier Purim seudah or to send more shalach manos (Rambam, Hilkhos Megillah 2:17).
Even a poor person who receives charity must give Matanos l’Evyonim (Bach, Tur on Shulchan Aruch 694). The minimum amounts for this gift vary from “two small coins” to “a respectful amount”, but all Torah authorities agree that one should give the recipients something to benefit their celebration of Purim (Pri Megadim, Mishbetzos Zahav 694:1).
Money for Matanos l’Evyonim can be designated before Purim because if the poor person receives the money on Purim, one fulfills the mitzvah (Be’er Heiteiv 695:7; Aruch HaShulchan 694:2).
A woman is obligated in Matanos l’Evyonim (Shulchan Aruch 695:4). Although a married woman may be included in the gift given by her husband, the Magen Avraham encourages a married woman to distribute money to the poor herself on Purim.
One may not use money collected for Matanos l’Evyonim for a different tzedakah (Bava Metzia 78b).