Exodus 30:13

Aaron shall make atonement on its horns once in the year; with the blood of the sin offering of atonement once in the year he shall make atonement for it throughout your generations. It is most holy to the LORD.”

The LORD spoke to Moses, saying,

“When you take a census of the children of Israel, according to those who are counted among them, then each man shall give a ransom for his soul to the LORD when you count them, that there be no plague among them when you count them.

Everyone who passes over to those who are counted, from twenty years old and upward, shall give the offering to the LORD.

The rich shall not give more, and the poor shall not give less, than the half shekel, when they give the offering of the LORD, to make atonement for your souls.

You shall take the atonement money from the children of Israel, and shall appoint it for the service of the Tent of Meeting; that it may be a memorial for the children of Israel before the LORD, to make atonement for your souls.”