https://www.nbcsports.com/nfl/profootballtalk/rumor-mill/news/tua-tagovailoas-contract-has-no-concussion-clauses-exceptions-or-waivers
If Tua retires — after being cleared to play — Tua would lose the balance of the guarantees. Also, if the Dolphins were inclined to exercise their right to recover paid but unearned signing bonus money, they could seek $8.4 million for each year remaining on the contract (through 2028), along with $466,667 for each game left in 2024 after he’s cleared.
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The Dolphins meanwhile face the prospect of paying more than $167 million over the next three years, if Tua isn’t cleared to play. The real dollars also become cap dollars that the Dolphins wouldn’t have for other players.
It sets up an awkward dance. In the end, there could be a negotiated compromise, with for example Tua retiring and Miami retaining half of the $167 million.