The Rama (Orah Haim 694:1) writes that there is a custom of giving three coins each equal to half the basic unit of currency in that locale (half-dollar, half-pound, etc.) to fulfil the obligation of Mahatzit HaShekel. This is based on the section ofParashat Ki Tisa dealing with the commandment of Mahatzit HaShekel, in which the word “Teruma” (lit. donation) is mentioned three times. Rabbi Yehuda Ayash (Mateh Yehuda), however, says that one mention of “Teruma” refers to donations for the sockets of the Mishkan, another alludes to donations for the remainder of the Mishkan and that only one reference of “Teruma” alludes to the census ofMahatzit HaShekel. As such, he explains that only one coin equal to half the basic unit of currency need be given for Mahatzit HaShekel, and according to Rabbi David Ovadia (Nahagu Ha’am), this is the Moroccan custom as well. The Kaf HaHaim (O.H. 694:20) writes that the value of the Mahatzit HaShekel nowadays is equivalent to the value of 3 Dirhams of silver, which given the current price of silver, is approximately USD $6. If one wishes to be stringent one can donate this value for each member of one’s family, although this is not our custom.
It should be noted that one may not use funds allocated for Ma’aser for the fulfillment of Mahatzit HaShekel. Furthermore, one should refer to this Mitzvah as “Zecher LeMahatzit HaShekel” (lit. a commemoration of the half-shekel) because by simply calling it Mahatzit HaShekel, there is a concern that the money thereby becomes consecrated and its use restricted.
Summary: One fulfils Zecher LeMahatzit HaShekel by donating half the basic unit of the local currency, such as a half-dollar in the United States. v