Exodus 30:12-16

“When you take a census of the sons of Israel to count them, then each one of them shall give a ransom for himself to the Lord, when you count them, so that there will be no plague among them when you count them.

This is what everyone who is counted shall give: half a shekel according to the shekel of the sanctuary (the shekel is twenty gerahs), half a shekel as a contribution to the Lord.

Everyone who is counted, from twenty years old and over, shall give the contribution to the Lord.

The rich shall not pay more, and the poor shall not pay less, than the half shekel, when you give the contribution to the Lord to make atonement for yourselves.

And you shall take the atonement money from the sons of Israel and give it for the service of the tent of meeting, so that it may be a memorial for the sons of Israel before the Lord, to make atonement for yourselves.”