Burnley broke their transfer record to recruit Robbie Brady from Norwich on transfer deadline day.
The Republic of Ireland international signed a three-and-a-half-year deal at Turf Moor for an undisclosed fee.
But the Clarets confirmed the sum eclipsed the £10.5million they paid Derby for Jeff Hendrick last summer.
Brady spent 18 months at Norwich, having joined from Hull for £7million, and was part of the team relegated from the Premier League last season.
He was the second new arrival at Burnley on Tuesday with Sean Dyche also signing Ashley Westwood from Aston Villa.