Northampton Saints have been fined £60,000 by Premiership Rugby for allowing George North to play for Wales against Australia last month.
The club admitted that they breached policy by releasing the winger outside of the International Rugby Board's international window.
The Saints have decided not to appeal the decision, which was made by a three-man panel.
Northampton return to Aviva Premiership action on Saturday when they make the trip to London Wasps.