As Matthew's account of Jesus's journey to Jerusalem and the crucifixion continues, we now follow Jesus and his disciples on their journey back to Galilee from Caesarea Philippi. Most likely, they returned to Peter's home in Capernaum where Jesus often rested and launched out again in ministry.
Per Jesus' usual methods, HE uses common events to teach his disciples great lessons about the Kingdom of Heaven. The lesson in this passage concerns one's citizenship in Heaven. This lesson comes through an expression of Divine Ability to provide for a tax debt.
If Jesus can miraculously pay for a tax debt that he is not really bound to pay, certainly then HE can miraculously pay for a sin debt for all sinners that he is not really bound to pay. This scene with tax collectors foreshadow the sacrificial sacrifice of our LORD for all sin.