During his rookie season in the OHL, Tavares competed for Team Ontario in the 2006 World U-17 Hockey Challenge in Saskatchewan as a 15-year-old, but failed to medal. Later that year, at the end of the 2005–06 season, he was selected to join Canada's under-18 team for the 2006 IIHF World U18 Championships in Sweden, but failed to medal once more, falling to the Czech Republic in the bronze medal game. Later in the off-season, he was invited to the under-18 team's summer training camp to prepare for the 2006 Ivan Hlinka Memorial Tournament in the Czech Republic and Slovakia, though an injury ultimately prevented him from participating.