Exodus 30:13-16

13This they shall give, every one that passeth over unto them that are numbered, half a shekel after the shekel of the sanctuary: (the shekel is twenty gerahs:) half a shekel for an offering to the LORD.

14Every one that passeth over unto them that are numbered, from twenty years old and upward, shall give the offering of the LORD.

15The 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.

16And thou shalt take the atonement money from the children of Israel, and shalt 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.