Basic Age and High School Requirements
All NBA Draft eligible players must be at least 19 years old. Additionally, they must be at least one year removed from their high school graduation. This means a player cannot enter the draft straight out of high school. They must wait at least one year, which is typically spent either playing college basketball or playing professionally overseas.
College Player Rules
College basketball players who want to enter the NBA Draft must declare their eligibility by a specific deadline set by the NBA each year, usually in the spring. College players can enter the draft early and still maintain their college eligibility if they withdraw before the deadline. If they do not withdraw by the deadline, they lose their college eligibility. Players can also complete their college degree and enter the draft after graduation with no restrictions.
International Player Requirements
International players must be at least 22 years old in the calendar year of the draft to be eligible. However, international players who declared early entry before age 22 may still be eligible if they meet the original one-year-from-high-school requirement. These players are typically those who have played professionally in foreign leagues.
Declaring and Withdrawing from the Draft
Players who are unsure about entering the draft can participate in the draft evaluation process and still withdraw before the official declaration deadline. This allows them to test the waters, receive feedback from NBA teams, and then decide whether to stay in the draft or return to college. Once the deadline passes, their decision is final for that year.
No Professional Experience Restrictions
There are no restrictions against players who have played professionally before entering the draft. Players can have played in foreign leagues, minor leagues, or other professional basketball leagues and still be eligible for the NBA Draft as long as they meet the age and high school graduation requirements. 
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