Barcelona have registered Sergio Aguero after Sergio Busquets and Jordi Alba accepted salary reductions.
The Spanish giants announced the addition of Manchester City's record goalscorer in May but new financial fair play rules in the country restricted the La Liga club from registering new signings.
Earlier in August, Gerard Pique took a pay cut to allow Memphis Depay, Eric Garcia and Rey Manaj to officially be registered and a similar situation has seen Aguero's signing finally ratified.
An official club statement read: "The salary reductions for Sergio Busquets and Jordi Alba, two of the four first-team captains, signed this Tuesday have allowed FC Barcelona to achieve two objectives: the registration of Sergio Aguero with the Spanish Football League (LFP) and to extend the club's limit with regards to financial fair play regulations.
"Sergio and Jordi Alba have agreed to changes in the financial terms of their contracts which included a wage reduction for this season and the deferment of payments for the remaining years.
"The gesture from the two players comes after the agreement recently signed by Gerard Pique which also allowed his team-mates Memphis, Eric Garcia and Rey Manaj to be registered with the league.
"As such, FC Barcelona has completed the registration of its players with the LFP."
Aguero will still be forced to wait before he can debut for his new club after he sustained a calf injury at the beginning of August which is likely to rule him out until October.
The Argentinian has endured a troubled start to life at Barcelona, after compatriot Lionel Messi departed the Nou Camp in shock fashion with financial fair play rules preventing the La Liga club from registering Messi's new deal, which saw the six-time Ballon D'Or winner leave and subsequently sign for Paris St Germain.