2010-11: Nick Schmaltz skated for the Chicago Mission U16 midget team in Illinois. In 32 games he scored 19 goals with 35 assists and had 22 penalty minutes. Schmaltz participated in USA Hockey's Select 15 Festival in July 2011.
2011-12: Schmaltz made his USHL debut — skating in 11 games with the Green Bay — and played for the Chicago Mission U16 team. He also played for the USA U16 team in the 2012 Winter Youth Olympic Games. He scored 1 goal with 3 assists and was +7 with 2 penalty minutes in 11 USHL games and scored 23 goals with 23 assists in 25 games for Chicago Mission. Schmaltz was one of three players to lead the USA with six points at the YOG. He scored 2 goals with 4 assists and was +2 with 8 penalty minutes in six games. The USA lost to Canada, 7-5, in the bronze medal game. Schmaltz was selected by Windsor in the fourth round (76th overall) of the 2012 OHL Priority Draft despite making a commitment to join his older brother Jordan at the University of North Dakota in 2014-15.
2012-13: Schmaltz was one of four players to skate in all 64 games for Green Bay and was the Gamblers fourth-leading scorer as a 16-year-old. He scored 18 goals with 34 assists and was +2 with 15 penalty minutes. The defending Clark Cup champions finished second in the East Division and lost to Youngstown in a first round series. Schmaltz scored 1 goal with 1 assist and was -2 in four playoff games.
2013-14: Schmaltz skated for the USA's U18 team at the 2013 Ivan Hlinka Memorial Tournament before returning to Green Bay for his second USHL season and participated in the 2013 CCM/USA Hockey All-American Prospects Game in September. Schmaltz led all scorers with five goals in five games at the Ivan Hlinka tournament and his eight points were tied for second behind Canada's Spencer Watson (10). The USA lost to Canada, 4-0, in the gold medal game. Schmaltz played for the USA at the 2013 U19 World Junior A Challenge; scoring 2 goals with 4 assists and finishing +2 with 8 penalty minutes in six games for the gold medal squad.