Reference for Chullin 50:31
<big><strong>מתני׳</strong></big> התמד עד שלא החמיץ אינו ניקח בכסף מעשר ופוסל את המקוה
BROTHERS WHO ARE PARTNERS [IN THEIR INHERITANCE], WHEN THEY ARE LIABLE TO PAY THE AGIO,<span class="x" onmousemove="('comment',' Heb. from Greek **. This was a small coin which every person had to add to his annual contribution of a half-shekel to the Temple in order to compensate the Temple Treasury for the loss it might sustain on exchanging the half-shekel for other coinage. It was not permissible for two people to evade this additional payment by combining and paying one shekel between them. On the other hand, this law of agio was relaxed in favour of a person who paid the half-shekel on behalf of another by way of gift to that other person; and therefore, if a father paid a whole shekel on behalf of his two sons by way of gift to them, he was not liable to pay any agio at all. In the case of our Mishnah the circumstances are that the brothers had divided the inheritance on the death of their father and subsequently entered into partnership; consequently each one must pay the agio when contributing his half-shekel even though they pay one whole shekel jointly, in the same way as when two people pay together one whole shekel.');"><sup>17</sup></span>