Exodus 30:12-16

12“When you take a census of the Israelites to number them, each man must pay the LORD a ransom for his life when he is counted. Then no plague will come upon them when they are numbered. 13Everyone who crosses over to those counted must pay a half shekel,1 according to the sanctuary shekel, which weighs twenty gerahs.2 This half shekel is an offering to the LORD.

14Everyone twenty years of age or older who crosses over must give this offering to the LORD. 15In making the offering to the LORD to atone for your lives, the rich shall not give more than a half shekel, nor shall the poor give less. 16Take the atonement money from the Israelites and use it for the service of the Tent of Meeting. It will serve as a memorial for the Israelites before the LORD to make atonement for your lives.”