In Masechet Shekalim (1:6)
וְאֵלּוּ שֶׁחַיָּבִין בַּקָּלְבּוֹן, לְוִיִּם וְיִשְׂרְאֵלִים וְגֵרִים וַעֲבָדִים מְשֻׁחְרָרִים, אֲבָל לֹא כֹּהֲנִים וְנָשִׁים וַעֲבָדִים וּקְטַנִּים. הַשּׁוֹקֵל עַל יְדֵי כֹּהֵן, עַל יְדֵי אִשָּׁה, עַל יְדֵי עֶבֶד, עַל יְדֵי קָטָן, פָּטוּר. וְאִם שָׁקַל עַל יָדוֹ וְעַל יַד חֲבֵרוֹ, חַיָּב בְּקָלְבּוֹן אֶחָד
The following are liable [to pay] the kalbon (surcharge): Levites and Israelites and converts and freed slaves; but not priests or women or slaves or minors. If a man paid the shekel on behalf of a priest, or on behalf of a woman, or on behalf of a slave, or on behalf of a minor, he is exempt. If a man paid the shekel on his own behalf and on behalf of his fellow he is liable for one kalbon.
The next mishna explains that when one gives his friend’s half shekel as a present (meaning, he doesn’t expect to be payed back), he doesn’t need to pay a kalbon. He only needs to pay a kalbon when he lends his friend a half shekel.
However, both this mishna and the next, and Kehati, do not specify when one is patur if he pays for a kohen etc. In a case where he lends them a half-shekel, or in a case where he gives it as a present? To make this even more confusing, this halacha( that he doesn’t need to pay a kalbon if he gives for himself and a kohen) is mentioned right before the Halacha when he lends a kalbon to his friend, but in the language of giving as a predent (על ידי).
So does a man need to pay a kalbon if he lends a half-shekel to a kohen, or not?