According to BBC Sports, UK Anti-Doping revealed that it cost around £600,000 [$836,166] - 10% of its annual budget - to pursue its doping case against former IBF, IBO, WBA, WBO heavyweight world champion Tyson Fury (24-0, 18 KOs).
UKAD claimed that Fury tested positive for banned steroid nandrolone in February 2015.
The former champion blamed the positive test on eating uncastrated wild boar.
Fury, 29 years old, has not fought since beating Wladimir Klitschko to win the IBF, WBA, IBF and WBO world titles in November 2015.
He is currently training for a planned comeback on a yet to be announced date in April.
Late last year, Fury reached an settlement with UKAD - where he accepted a backdated two-year ban.
The settlement was no surprised, because UKAD revealed in November 2017 that it feared bankruptcy if a full blown legal war broke out with the boxer.
However, UKAD denied claims that the looming threat of a potential lawsuit against loss of Fury's in-ring earnings played a role in the decision to allow the fighter to resume his career.
Fury's boxing licence was reinstated last month by the British Boxing Board of Control (BBBofC), a decision that set the stage for his return.
Fury's long stint of inactivity is due to his battle with substance abuse and deep depression.
He was scheduled to rematch Klitschko on two separate dates in 2016. He withdrew from both cards and then eventually revealed that his mental state was a bad place and he was abusing cocaine and alcohol. After testing positive for the drug, the BBBoC removed him of his license. Sensing that his license was likely in jeopardy, Fury vacated his world titles.
All four of the belts that Fury captured will be up for grabs on March 31 in Cardiff, when IBF, IBO, WBA champion Anthony Joshua collides with WBO world champion Joseph Parker at Principality Stadium.