Luciano Acosta, left, led the team with 11 assists this season. (By Tony Quinn)

D.C. United has finalized the acquisition of Luciano Acosta from Boca Juniors, paying the highest transfer fee in organization history to secure the return of the club’s most creative player after he spent the 2016 MLS season on loan from the Buenos Aires titans.

United exercised its option to purchase the 22-year-old Argentine for an estimated $1.4 million, a decision long anticipated after Acosta raised his performance in the second half of the season. Club officials had been working out the final details in recent weeks.

In addition, United reworked Acosta’s contract. Terms of the multiyear pact were not disclosed. United will use targeted allocation money to offset his 2017 salary, meaning he will not be classified as a designated player until 2018. TAM funds are available for players earning more than the maximum salary cap hit ($457,500 in 2016) and less than $1 million.

This season, according to MLS Players Union figures, Acosta received $327,272 in base salary and $429,272 overall. United used TAM funds on his deal this year as well to help offset loan fees and other expenses.

The transfer payment is a departure for United, a money-losing organization that reports one of the lowest payrolls in the league annually and doesn’t typically purchase players from abroad. In 2004, the club bought Argentine midfielder Christian Gomez from Arsenal de Sarandi, and in subsequent years has paid loan fees for players.

The total investment in Acosta (transfer fee plus salary) is the highest since Argentine midfielder Marcelo Gallardo in 2008.

The move to acquire Acosta long term comes as United sees a brighter financial future with a new stadium scheduled to open at Buzzard Point in the summer of 2018. The club aims to break ground this winter.

“This substantial investment demonstrates our ownership’s commitment to our continued success on the pitch in the coming years,” Dave Kasper, United general manager and VP of soccer operations, said in a written statement. Kasper identified Acosta during a scouting trip last year.

The 5-foot-3 playmaker overcame an erratic early season — including a sideline argument with Coach Ben Olsen during a match in Philadelphia — to become an influential force in United’s playoff push. He led the team in assists with 11 and scored three goals in 31 regular season appearances (25 starts).

With Acosta’s deal done, United will now turn attention to re-signing free agent defender Sean Franklin; upgrading and extending defender Steve Birnbaum’s contract; finalizing its protected list for the Dec. 13 expansion draft; and preparing for the re-entry and college drafts this winter. Olsen said the club plans to keep the core of the roster together and look to add a few pieces.