The East Coast has been docked two competition points and the union fined $3000 after fielding an ineligible player in a Ranfurly Shield challenge and the Heartland Championship.
The New Zealand Rugby Union imposed the penalty after East Coast lock Everard Reid was found to have been ineligible to be classed as a local player, after he made a club rugby appearance for a Hawke's Bay club.
Reid played in the Ranfurly Shield challenge against Waikato in July and in two Heartland Championship matches against Horowhenua Kapiti and King Country.
East Coast has now completed the relevant documentation for Reid to be classed as a loan player, for the remainder of the season.
The NZRU panel emphasised the importance of maintaining integrity around the eligibility rules and noted that while the breaches were not deliberate, they reflected an unacceptable lack of care and the East Coast union's previous breaches for similar offences in 1998 and 2004 was noted.
East Coast admitted the breaches and half the fine will be suspended for five years, provided the union doesn't breach the rules again during that period.
The deduction of the competition points doesn't alter East Coast's position in the Heartland Championship, they still remain in eleventh spot.