Of each man, i.e. of each of those wealthy Israelites. But as each of these were not equally wealthy, so it is not probable that he taxed them equally. Others therefore render it to or for each man, i.e. for every Assyrian soldier; which interpretation is favoured by the placing of the words in the Hebrew text, which differs from that in our translation.
Related Commentaries of 2 Kings 15:20
2 Kings 15:20
20 And Menahem exactedc the money of Israel, even of all the mighty men of wealth, of each man fifty shekels of silver, to give to the king of Assyria. So the king of Assyria turned back, and stayed not there in the land.