Mt 17:22-27
22As [Jesus and his disciples] were gathering in Galilee, Jesus said to them, “The Son of Man is to be handed over to men, 23and they will kill him, and he will be raised on the third day.” And they were overwhelmed with grief.
24When they came to Capernaum, the collectors of the temple tax approached Peter and said, “Doesn’t your teacher pay the temple tax?” 25“Yes,” he said. When he came into the house, before he had time to speak, Jesus asked him, “What is your opinion, Simon? From whom do the kings of the earth take tolls or census tax? From their subjects or from foreigners?” 26When he said, “From foreigners,” Jesus said to him, “Then the subjects are exempt. 27But that we may not offend them, go to the sea, drop in a hook, and take the first fish that comes up. Open its mouth and you will find a coin worth twice the temple tax. Give that to them for me and for you.”
Temple Tax: Ruled by Rome through the procurators and vassal kings, the Jewish people were burdened with four principal kinds of duties: a land tax, a poll tax and a tax on personal property, export and import customs at seaports and city gates, and in Jerusalem a house tax.
Aside from the tribute and taxes due foreign rulers, the people were also taxed individually with a half-shekel payment annually for the temple. This is called the didrachma or double drachma.
The background of the temple tax was the half-shekel atonement money required of all males twenty years and above (Ex 30:11-16). In Nehemiah’s time, the Jews paid a third of a shekel to the temple. This was later changed to a half-shekel which was collected annually from every Jew twenty years and above all over the world. After the fall of Jerusalem and the destruction of the temple in 70 AD, Josephus narrates that the Roman emperor Vespasian ordered all Jews to continue the tribute payable annually for the Capitol in Rome (see War VII. vi. 6).
The exchange between Jesus and Peter probably reflects the duties of the Christians in Luke’s time. Jesus—and the believers—are the king’s (God’s) sons and are exempt in principle from paying the tax. By paying even though he does not owe anything, Jesus makes Peter understand that Christians should shoulder their duties as ordinary citizens however unpleasant these might be.