Florian Wirtz: How do football transfer add-ons work?

These extra amounts certainly add up. Let’s take Manchester United as an example.

In their third-quarter financial results for 2024-25 – announced on 6 June – deep down on page 45 of 47, United confirmed that “under the terms of certain contracts with other football clubs and agents in respect of player transfers, additional amounts, in excess of the amounts included in the cost of registrations, would be payable if certain substantive performance conditions are met”.

United confirmed that as of 31 March 2025, the potential liability was £138.82m. Of that, £112.25m was related to player appearances, team success or new contracts, while £3.19m was around international appearances and £22.03m was related to ‘awards’, with the rest classed as ‘other’.

That entry goes some way to explaining what add-ons are and how they can tot up.

When he signed for United, the club let it be known that one of the add-ons attached to Anthony Martial’s £36m move from Monaco was connected to the France striker winning the Ballon d’Or. This was never realised.

United were also very quick to reject speculation Mason Mount had triggered one of the add-ons included in his transfer from Chelsea by playing for the club in a European final, the Europa League final defeat by Tottenham in May.

The Martial Ballon d’Or one was clearly far more difficult, although United argued at the time that if the forward reached that level of success, they would happily pay the clause on the basis they would have benefited enormously through results on the pitch.

This article is the latest from BBC Sport’s Ask Me Anything team.