In the New Testament, Matthew is identified as a tax collector before following Jesus. Matthew 9:9 describes Jesus calling a man named Matthew from his tax booth, and the man immediately becomes a disciple.
Tax collectors worked for the Roman administration or its local contractors and were widely disliked in Jewish society. Their occupation connected them with foreign rule and could involve financial exploitation, so the calling of a tax collector carried a strong social message.
Mark and Luke tell a closely related calling story but name the tax collector Levi rather than Matthew. Christian tradition commonly identifies Matthew and Levi as the same person, though the texts do not explain the name difference.
Matthew is listed among the Twelve in the Gospel lists. Later tradition also associates him with the Gospel of Matthew, but the Gospel itself does not explicitly name its author.