La Liga's strict spending limits restricted Olmo's initial registration to December 31, 2024 after Barcelona made the Spain playmaker their flagship signing last summer.
The club was left scrambling for alternatives to get Olmo on the books before the clock struck midnight in Spain, having exhausted legal avenues to extend the registration to June 30, 2025.
A Barcelona court on Monday rejected a request to extend the registration, after a commercial court in the Catalan capital made the same decision last week.
The heavily indebted club registered Olmo with 80 percent of injured defender Andreas Christensen's pay thanks to an exception allowing clubs to replace long-term absentees.
The commercial court argued that overspending was authorised to prevent a long-term injury undermining a team's competitiveness but not to register players whose wages exceeded the salary limit.
Spanish media reported that Barcelona had submitted documents to La Liga on Tuesday showing it would generate 100 million euros ($103 million) to finance Olmo's registration by selling VIP seats at its future expanded Camp Nou stadium.
Olmo's contract, initially set to run until 2030, includes a clause that would release him if he could not be registered, according to Spanish media.
The Spain playmaker's potential departure due to an administrative imbroglio would be a damaging and embarrassing blow to the third-placed Blaugrana's title bid.
The 26-year-old has notched five goals in La Liga this season and starred as Spain clinched Euro 2024 glory in Germany.
