When Manchester United signed Andrey Santos from Chelsea this summer for £50m, the fee got all the coverage. The more interesting number sat one line further down: Chelsea kept a 10 per cent sell-on clause. Sky Sports and ESPN both carried it, and Manchester United's own announcement confirmed the deal's structure.
Read that clause plainly and it says something no press release would: Chelsea think there is a version of the future where Andrey Santos is worth a lot more than £50m, and they want a seat at that table without doing any of the work.
That is what a sell-on clause is. A claim on a future that has not happened yet, written by the club walking away.
What the clause actually says
A sell-on clause entitles the selling club to a percentage of a future transfer fee if the player is later sold to a third club. It sits in the transfer agreement between the two clubs. The player is not a party to it, does not owe anything under it, and in most cases has no idea what the number is.
Three things have to be true before a penny moves. The player has to be sold again, for an actual fee, while the clause is in force. Miss any of the three and the clause is worth exactly nothing, which is a detail the coverage tends to skip and the second half of this page keeps returning to.
Gross or profit: the distinction that moves millions
The percentage is the number that gets reported. The base it applies to is the number that matters, and there are two versions.
A gross clause takes the percentage of the entire future fee. Ten per cent of a £60m sale is £6m, full stop.
A net clause, far more common at the top level, takes the percentage of the profit: the future fee minus what the middle club originally paid. Same £60m sale, but the middle club paid £30m, so the profit is £30m and the same 10 per cent yields £3m. Half the money on identical headlines.
Selling clubs know this, which is why net clauses tend to carry bigger percentages. Twenty per cent of profit can be worth less than ten of gross. When a fee is announced "with a sell-on", the single most useful question is the one almost never answered in print: of what?
Jude Bellingham, and the payout nobody could agree on
Birmingham City sold Jude Bellingham to Borussia Dortmund in 2020 for a fee reported around £25m, with a sell-on clause attached. Three years later Dortmund sold him to Real Madrid for an initial €103m, as AFP reported at the time.
So Birmingham got rich. How rich depends on which paper you read. The Times put Birmingham's cut at more than £6m. GiveMeSport reported £10m. Other outlets landed anywhere between £4m and the top of that range, and the percentage itself was reported at different values depending on who was doing the reporting.
None of these outlets was inventing things. The clause is a private commercial term between two clubs, the leak comes out in pieces, and every piece gets printed as the whole. The same gap between announced fee and actual money runs through how transfer fees are actually paid, and the sell-on clause is the most private term of the lot. Treat any reported sell-on figure as a claim by one source, not a fact of the deal.
Dele Alli, and the clause that paid nothing
MK Dons sold Dele Alli to Tottenham Hotspur in 2015 for an initial £5m, a fee the BBC covered at the time, and kept a sell-on clause reported at 20 per cent.
For seven years it looked like one of the great pieces of lower-league business, on paper worth a fortune while Alli was being valued in the tens of millions. Then Tottenham Hotspur let him go to Everton in 2022 on a deal with no guaranteed fee, structured entirely around appearance-based add-ons.
Twenty per cent of nothing is nothing. MK Dons' return depended on the add-ons being triggered, not the clause they had spent seven years holding.
A sell-on clause is a lottery ticket where a bigger club controls the draw. The middle club decides when to sell, whether to sell, and how the deal is structured. Run the contract down, or move the player on a free, or swap him in a player-plus-cash arrangement, and the percentage evaporates legally and completely.
Why clubs agree to them at all
Because the clause is a compromise instrument, the same family as the add-on. It exists to close a gap between two clubs who cannot agree what a player is worth today.
The seller thinks the player will be great and wants tomorrow's price. The buyer will only pay today's. The sell-on clause lets both be right: the buyer pays the lower fee now, and if the seller's version of the future arrives, the seller collects a share of it. The buyer gives up a slice of a hypothetical; the seller accepts less cash for a story.
Which is why the presence of a sell-on clause in an announcement tells you something real about the negotiation. Chelsea taking 10 per cent on Andrey Santos means Chelsea priced in a future Manchester United would not pay for up front. A deal with no sell-on and no add-ons, like Arsenal's flat £75m for Bruno Guimaraes this same window, means nobody needed the argument deferred.
What a sell-on clause is not
Two neighbours cause constant confusion.
The FIFA solidarity mechanism also pays a percentage of a transfer fee to former clubs, but it is not negotiated, it is regulation: 5 per cent of any international fee is distributed to the clubs that trained the player between 12 and 23. It applies whether anyone asked for it or not, and it pays youth academies, not the last selling club.
A buy-back clause gives the selling club the right to repurchase the player at a set price. A sell-on gives them money if he moves anywhere; a buy-back gives them the player if they want him. Clubs sometimes hold both, and the reporting routinely swaps one label for the other.
The take: the quiet confession in every percentage
A sell-on clause is the one place a selling club tells the truth about its own pricing.
Every window, clubs brief that they extracted full value, that the number was the number, that nobody leaves cheap. Then the paperwork keeps a percentage of the next sale, and the percentage says what the press release cannot: we know we might be wrong, and we are insuring against our own valuation.
There is nothing shameful in that. Selling a 21-year-old is pricing a decade of possibility with last season's evidence. The clause is the honest instrument in a business allergic to honesty about uncertainty.
The dishonesty arrives later, in how it gets reported. A fee "rising to" some total, a sell-on "worth" some figure, and none of it distinguishes gross from net, guaranteed from conditional, or a binding percentage from a club's hopeful arithmetic. The number that ends up in the graphic is routinely the biggest one available rather than the likeliest. The clause deserves better coverage, if only because it is the rare transfer term that admits the future is unknown.
Sources for verification
- Andrey Santos to Manchester United, £50m (£48m guaranteed plus £2m add-ons), Chelsea 10% sell-on: Manchester United official announcement; Sky Sports; ESPN.
- Bellingham to Borussia Dortmund 2020, fee ~£25m: BBC Sport; The Athletic.
- Bellingham to Real Madrid, initial €103m: AFP (carried by Malay Mail and Soccerway); The Times (Birmingham cut "in excess of £6m"); GiveMeSport (£10m) — figures conflict, presented as conflicting claims, not fact.
- Dele Alli to Tottenham Hotspur, initial £5m, 2015: BBC Sport. Sell-on reported at 20%: Milton Keynes Citizen; Spurs Web. Everton move with no guaranteed fee, add-on structured: BBC Sport; Sky Sports.
- Solidarity mechanism 5%, training clubs ages 12-23: FIFA Regulations on the Status and Transfer of Players (RSTP), Annexe 5.