Oscar Gobern could cost Huddersfield Town £400,000 after an independent tribunal set an initial fee of £275,000.
The deal also includes add-ons based on appearances which could eventually see the fee rise.
The 20-year-old midfielder who came through Southampton’s Apprenticeship programme moved to The Galpharm Stadium in the summer.
As Huddersfield and Southampton were unable to reach a deal his fee was set by a tribunal.
Terriers chief executive Nigel Clibbens said: “Although a tribunal is never the ideal situation when it comes to player transfers, we were happy that our submission was acknowledged and thoroughly taken into consideration by the independent panel of four.”
“We are happy that Oscar can now concentrate on his football and his embryonic career at Huddersfield Town.”
Meanwhile, Terriers striker Jordan Rhodes made his third appearance for Scotland Under-21s, playing the first 60 minutes in their goalless European Championship qualifier against Bulgaria at St Mirren Park last night.