From the IIHF rules:
To play in the IIHF World Championship, the Olympic ice hockey tournament and the qualifications to these competitions, players must fulfill the following qualification requirements:
- Each player must be under the jurisdiction of an IIHF member national association.
- Each player must be a citizen of the country he represents.
Acquiring a new national eligibility (The ‘two-year’ case)
When a player has changed his citizenship or has acquired another citizenship and wants to participate for the first time in an IIHF competition representing his new country he must:
- Prove that he has participated for at least two consecutive hockey seasons and 16 consecutive months (480 days) in the national competitions of his new country after his 10th birthday during which period he has neither transferred to another country nor played ice hockey within any other country. Female players need to have participated on a consistent basis for at least one hockey season and have been member of the new national association for at least 12 consecutive months during that period.
- Have an international transfer card (ITC) that shows the transfer to the national association of his new country and which was approved and dated at least 16 months (480 days) before the start of the IIHF competition in which he wishes to participate.
Change of national eligibility (The ‘four-year’ case)
A player, who has previously participated in IIHF competition, can switch national eligibility (but only once in a player's life) if:
- He is a citizen of the new country of his choice
- He has participated for at least four consecutive years (1460 days) in the national competitions of his new country, during which period he has neither transferred to another country nor played ice hockey within any other country and has not played for his previous country in an IIHF competition during this four year period.
- He has an international transfer card (ITC) that shows the transfer to the national association of his new country and which was approved and dated at least four years before the start of the IIHF competition in which he wishes to participate.