FIFA has denied a request from Chelsea to postpone their transfer ban while they appeal the punishment.
Chelsea could now ask the Court of Arbitration for Sport (CAS) to grant an interim ruling, which would allow players to be signed in the off season.
Chelsea were banned from registering new players through January 2020 for breaking rules designed to protect teenage players.
The Premier League side were also fined more than £460,000, while the FA face a £390,000 sanction that they will also appeal, citing “concerns” with FIFA’s disciplinary processes.
The west London club were found guilty of 29 incidences of breaching article 19, which relates to the transfer of players aged under 18.
The club denies any wrongdoing and “categorically refutes the finding of the FIFA Disciplinary Committee”
In previous similar cases involving top Spanish clubs, FIFA granted provisional measures which meant transfer bans were not enforced during the appeal process.