Crystal Palace's deal for Alexander Sorloth could reach €18m.
Ekstra Bladet says Palace have paid FC Midtjylland €10m for the centre-forward, but the agreement has a series of built-in bonuses.
Should Palace stay up, FCM will be due another €2.3m - and the same amount will be due if they stay up the following season.
After 50 games, Palace will pay €2.5m - and €1m will be due after his first 25 games.
Sorloth left FCM for Palace with a record of ten goals in 19 games.