Mr. Caruana would not say who approached him, but the offer came after he won the Sinquefield Cup, obliterating an impressive field that included the world champion, Magnus Carlsen of Norway. The tournament is named for Rex Sinquefield, a retired financier active in Missouri politics who has become the primary benefactor of chess in the United States. Mr. Sinquefield provided the $315,000 prize fund for the event, as he also does for the United States Championship, which for seven consecutive years has been held at the Chess Club and Scholastic Center of St. Louis, which he financed and built.
Switching federations, particularly for an elite player, is not simple. A grandmaster, for example, and the federation he would like to play for must apply to the World Chess Federation, the game’s governing body, for permission, then pay a fee of up to 5,000 euros (about $5,400) if the player is to be allowed to represent his new country immediately. If the player has not been a resident of his new country for two years, an additional compensation fee to the player’s old federation is required — as much as €50,000 for a player of Mr. Caruana’s caliber.
Consequently, transfers of elite players are rare. In the last 15 years, there have been only two involving players ranked in the world’s top 20: Sergey Karjakin, a Ukraine-born player ranked No. 12 who now plays for Russia, and Wesley So, No. 8 in the world, who switched last year to the United States from the Philippines.
See the NYTimes article.