‘And when they were come to Capernaum, those who received the shekel came to Peter, and said, “Does not your teacher pay the didrachma (shekel)?” (Matthew 17:24).
The didrachma or shekel tax was probably that payable to the Temple treasury. It was payable yearly by Jews around the world, and contributed greatly to the Temple funds. It was an indication of their submission to God as His servants. Note the stress here on whether Jesus paid it. Peter, of course, had to pay it as well, and they may have approached him as the head of the house in which they were staying (compare Matthew 8:14). But the whole point of this narrative is as to whether Jesus should have to pay it (‘does not your teacher pay?'), although it does then lead on to the question as to whether any ‘son of God' should pay it.
Jesus has, of course, with some of His disciples, been out of range of the collectors. Thus it is only when He arrives home that He is approached through Peter. As Passover was approaching the tax was due to be paid. The indirect question was probably simply a courtesy, but it raised the right background against which Jesus could make His position clear to Peter. The collectors did, of course, expect the answer to be ‘yes'.