N.J. Admin. Code § 18:35-5.1
Example 1: Player A, a member of a professional athletic team, is a nonresident of New Jersey. Player A's contract for such team requires A to report to the team's training camp and to participate in all exhibition, regular season, and playoff games. Player A has a contract which covers seasons that occur during year 1/year 2 and year 2/year 3. Player A's contract provides that A receive $ 500,000 for the year 1/year 2 season and $ 600,000 for the year 2/year 3 season. Assuming Player A receives $ 550,000 from such contract during taxable year 2 ($ 250,000 for one-half the year 1/year 2 season and $ 300,000 for one-half the year 2/year 3 season), the portion of such compensation received by Player A for taxable year 2, attributable to New Jersey, is determined by multiplying the compensation Player A receives during the taxable year ($ 550,000) by a fraction, the numerator of which is that total number of duty days Player A spends rendering services for the team in New Jersey during taxable year 2 (attributable to both the year 1/year 2 season and the year 2/year 3 season) and the denominator of which is the total number of Player A's duty days spent both within and without New Jersey for the entire taxable year.
Example 2: Player B, a member of a professional athletic team, is a nonresident of New Jersey. During the season, B is injured and is unable to render services for B's team. While B is undergoing medical treatment at a clinic in New Jersey, B's team travels to New Jersey for a game. The number of days B's team spends in New Jersey for practice, games, and meetings while B is present at such clinic in New Jersey shall not be considered duty days spent in New Jersey for Player B for that tax year, but such days are considered to be included within total duty days spent within and without New Jersey.
Example 3: Player C, a member of a professional athletic team, is a nonresident of New Jersey. During the season, C is injured and is unable to render services for C's team. C performs rehabilitation exercises at the facilities of C's team in New Jersey as well as at personal facilities in New Jersey. The days C performs rehabilitation exercises in the facilities of C's team are considered duty days spent in New Jersey for Player C for that tax year for purposes of this section. However, days Player C spends in private facilities in New Jersey shall not be considered duty days spent in New Jersey for Player C for that tax year, but such days are included within total duty days spent within and without New Jersey.
Example 4: Player D, a member of a professional athletic team, is a nonresident of New Jersey. During the season, D travels to New Jersey to participate in the annual all-star game as a representative of D's team. The number of days D spends in New Jersey for practice, the game, meetings, and other services for the team, shall be considered duty days spent in New Jersey for Player D for that tax year, as well as included in total duty days spent within and without New Jersey.
Example 5: Assume the same facts as given in Example 4, except that Player D is not participating in the all-star game and is not rendering services for D's team in any manner. Player D is traveling to and attending such game solely as a spectator. The number of days Player D spends in New Jersey for such game shall not be considered duty days spent in New Jersey. However, because the all-star game occurs during the regular season, such days are included in total duty days spent both within and without New Jersey.
Example 6: A nonresident member of a New Jersey professional athletic team has a season beginning with training camp on July 1. The season ends with the last regular season game on December 24. If the season is extended by playoff games after December 31, the additional duty days during the next calendar year will be duty days inside and outside New Jersey for the subsequent tax year.
N.J. Admin. Code § 18:35-5.1