A review into the payments of casual staff in September 2020 by the Australian Sports Commission (ASC) found 377 people were underpaid.
Of those, 315 current and former staff have received outstanding funds and 11 will receive payments next week.
"The ASC continues to try and contact the remaining 51 individuals," a spokesperson said.
The ASC did not reveal how much it owed staff.
"We are not in a position to disclose the financial terms at present," the ASC said.
"The ASC began processing payments to casual staff that were paid the incorrect ASC1 level minimum hourly rate in July."
However, the ABC is aware of two casual staff members at the Australian Institute of Sport's (AIS) Aquatic and Fitness Centre, which is operated by the ASC, who received $1,300 and $800 for back pay last year.
Both sought advice from the Fair Work Ombudsman.
Review into causal staff payments began in September 2020
The ASC launched a review into payments to casual staff in September 2020.
It told those affected that they would be reimbursed for any outstanding back pay once the review was complete.
It also said work was being done to ensure salary rates and allowances were correct moving forward.
"Issues relating to the underpayments were resolved in February 2022," the spokesperson said.
Staff at the AIS are employed under the ASC's enterprise agreement.
The agreement must match pay rates set by the Australian Government Industry Award and some staff are also eligible for allowances under the Fitness Industry Award.
