Shekalim, Chapter Two, Mishnah Two
This mishnah deals with various scenarios in which a person paid his shekel from money which did not belong to him.
1) One who gave his shekel to his fellow to pay it on his behalf, but [his fellow] paid it on behalf of himself: if the appropriation had already been made [his fellow] is guilty of sacrilege.
2) One who paid his shekel out of money belonging to the sanctuary:
a) If the appropriation had already been made and an animal [bought out of the appropriation] had already been offered, he is guilty of sacrilege.
3) [If he paid his shekel with] money that had been used to redeem the second tithe or the value of seventh year produce, he must eat food equal to its value.
Section one: A person received a shekel from his friend to pay his friends shekel but then used this money to pay his own shekel. If the shekel had already been counted in the Temples appropriation (and an animal purchased with that money and sacrificed, see below), then he is guilty of sacrilege. Sacrilege means that one has misappropriated funds or property which belongs to the Temple. Since this shekel had already been counted as belonging to the Temple and indeed had already been used, his action counts as sacrilege. He must now bring a special sacrifice and restore the value of that which he misappropriated (a shekel) plus another fifth.
Section two: In this case the person had in his possession money which he had previously donated to the Temple. He then tried to use that money to pay his shekel. Again the mishnah teaches that if the appropriation had already been made and if the shekel had been used to buy a sacrifice then he is guilty of sacrilege. We should note that according to the Talmud, in the previous section as well an animal had to have been sacrificed for it to be considered sacrilege.
Section three: Second tithe is usually redeemed with money and then the money is brought to Jerusalem and used there to buy food. If one sells seventh year produce, the proceeds from the sale have the same rules and restrictions that the produce itself hasany food which is purchased from this money must be used before seventh year produce must be removed from ones house (which is when that type of food is no longer found in the field). In the case in this mishnah someone uses this money (second tithe or seventh year produce proceeds) to pay his shekel. What he must now do is take another shekel and use it as if it was second tithe or seventh year produce money. This is sufficient to restore the shekel that he used to pay his shekel tax.