Charlton Athletic would have to give a portion of any fee they receive from Huddersfield Town for Alfie May to his previous club Cheltenham Town.
Addicks hitman May is wanted by the relegated Terriers, who are rebuilding under Michael Duff for life in League One next season.
Huddersfield are claimed to have now gone in with an offer for May.
While it is unclear how much Huddersfield have offered for May, Charlton must take into account a sell-on clause.
Cheltenham have a sell-on clause in May, according to journalist Jon Palmer.
Charlton signed May last summer and paid Cheltenham in the region of £250,000 to take him to the Valley.
He repaid the Addicks’ faith with 23 goals in League One which won the division’s Golden Boot.
The goals came despite Charlton finishing in the bottom half of the League One table and now Huddersfield want May to fire them to promotion next term.
