According to the source, Kansas City will trade its second-round pick in the 2013 draft, its second pick in the same round, and another conditional mid-round pick in 2014.
The trade cannot be officially completed until March 12, which is when the 2013 league year officially begins.
Smith, 28, has thrown for 14,280 yards with 81 touchdowns and 63 interceptions in 80 career games.
Bakcup quarterback Colin Kaepernick led the 49ers in the last 10 games of the year, including the Super Bowl.
