London - Cardiff City face a three-window transfer ban unless they pay the first instalment of the €17 million ($19M) transfer fee for Emiliano Sala to Nantes.
The Argentine, 28, died when the light aircraft he was travelling in from France to Britain crashed into the English Channel in January.
Cardiff and Nantes were unable to reach an amicable conclusion on the financial aspects of the move, so the case came before the Players' Status Committee (PSC) of FIFA.
The world governing body announced on September 30 that Cardiff must pay an initial €6 million to the French club.
Documents published on Monday, detailing the grounds for the decision, show that failure by Cardiff to pay the fee within 45 days of receiving bank details from Nantes following the ruling would mean "a ban on registering new players, either nationally or internationally, up until the due amounts are paid and for the maximum duration of three entire and consecutive registration periods".
According to a source close to Nantes, the French club sent bank details to Cardiff "at the beginning of October", which would mean the Welsh outfit has until mid-November to make the payment and thereby avoid a transfer ban. "Nantes expect everyone to fulfil their commitments and that the amount due to them is paid," the source told AFP.
Cardiff confirmed on Monday they would lodge an appeal against the decision to the Court of Arbitration for Sport (CAS) within the next two weeks.
They said the act of announcing they would appeal had effectively stopped the clock on the 45-day countdown.
The Championship club have argued that Sala was not officially their player when he died.
However, the PSC found that all the terms within the transfer agreement concluded between Cardiff and Nantes had been fulfilled.
The documents also show that Cardiff had sought a delay in the case until any other civil or criminal investigations into Sala's death had been completed.
But the PSC ruled that the dispute before it was "of a purely contractual nature" and that "Cardiff had not been able to prove that the outcome of those local proceedings would be relevant to the outcome of the dispute pertaining to whether or not a transfer fee is due".
The full fee payable for Sala was €17m, according to the FIFA documents.
The light aircraft Sala was travelling on came down during a night-time flight. His body was recovered, but that of the pilot, David Ibbotson, has never been found.
A report by Britain's Air Accidents Investigation Branch said Sala and the pilot were likely exposed to "potentially fatal" levels of carbon monoxide on the plane.
In the aftermath of the tragedy, Cardiff were relegated from the Premier League after just one season back in the top flight.