Shabbat Shekalim is named for the maftir reading, taken from the Torah portion “Ki Tisa” (the Book of Shmot, 30:11-16). The maftir describes a census requiring every Israelite man to contribute half of a shekel to support communal sacrifices in the Mishkan (and later at the Beit ha-Mikdash).
Shabbat Shekalim takes place on the Shabbat prior to Rosh Chodesh of Adar or on Shabbat Rosh Chodesh Adar itself. This year, being a leap year , when there are two months of Adar, Shabbat Shkalim falls on the 25 of Adar Alef.
“Parshat Shekalim” is the first of four special readings added during or immediately before the month of Adar. The other three are: