Opposition MPs say overpayment of federal public servants is only the latest issue for the troubled Phoenix pay system — and they worry that the approaching tax season will bring a fresh crop of problems.

Since the government consolidated many separate payroll systems into the Phoenix system last spring, tens of thousands of public servants have been underpaid, overpaid or not paid at all.

According to documents obtained by CBC News/Radio-Canada, more than 26,000 employees have been overpaid a total of about $68.6 million. Only about a third of the money sent out in error — around $22.3 million — has been recovered.

Edmonton MP Kelly McCauley, the Conservative deputy critic for public services, said his office has been "flooded" with calls from constituents who say they've been overpaid by the federal government.

"The money is sitting in their accounts, they brought it forward to the government, but it's not getting addressed," McCauley said. "There's no plan from the government."

NDP public service critic Erin Weir asks whether there may be 'unreported' cases of federal public servants being overpaid. (CBC)

The NDP's public services critic, Erin Weir, said the $68.6-million figure may not include workers who did not report being overpaid and that could create "a lot of uncertainty" for the public treasury.

"Of course, many federal employees have reported in good faith the fact they received these overpayments," Weir said. "But one wonders whether there may be more overpayments that have gone unreported."

Minister asks overpaid to come forward

According to Public Services and Procurement Minister Judy Foote, the government's first priority is to correct problems for underpaid and unpaid workers, and it will eventually turn to recouping taxpayer money that's been overpaid.

"We will get the money that's owed to the government, money that's been overpaid, when we get to those cases," she said.

"I encourage any employees who are getting more money than they are entitled to, maybe, put that money into a separate bank account."

She added that the government will work out a "respectful" process for overpaid workers to arrange either a lump-sum payment or repayment plan.

Minister of Public Services and Procurement, Judy Foote, says that the government's first priority is to get people paid, then it will try and recover overpayments worth almost $70 million. 1:09

In a statement, Public Services and Procurement Canada said the department's priority is timely and accurate pay, but there have been some former employees who've continued to receive pay cheques after they've left government.

"Right now, we are not promptly processing pay transactions, and this means that many employees who have left the public service or changed jobs continue to receive pay that should have been stopped," the statement said.

The statement goes on to say that happened in the old system as well and the department is working to reduce the frequency of those instances.

"For example, we now have a system that flags any payment over $10,000 so that departments and agencies can validate these amounts before payments are made," the statement said.

'It didn't seem fair'

Andrew Caddell was working for the government of Newfoundland and Labrador during what was supposed to be an unpaid leave from his job with the federal government. But he said paycheques continued to be deposited into his bank account over a three-month period, some after he reported the error.

He calculates that he was improperly paid about $16,000 due the Phoenix pay system. The government has asked him to pay back $3599.62 — a quarter of the total amount.

"Clearly they don't have a clue as to how much I really do owe," Caddell told CBC News.

Andrew Caddell says he was overpaid $16,000 due a Phoenix pay system error and he's trying to pay it back. (CBC)

Caddell said he couldn't live with himself if he didn't pay the entire sum back and he's seen the struggles other public servants have been going through because of the pay issues.

"There are people who are having nervous breakdowns, terrible, terrible problems — and meanwhile I was being overpaid. It didn't seem fair."

T4s as the next chapter?

Opposition MPs suggest that the next major issue for the government will be income-tax forms, which may not properly reflect the salaries or pay of public servants due to the Phoenix problems.

"With T4s coming out next week, we're going to see a new disaster coming out," McCauley said. "This is part of the ongoing cycle of incompetence from the minister."

Foote said the government is working to make sure public servants have the right paperwork, and that's another reason to for people to come forward.

"We are working with the Canada Revenue Agency to make sure that they have the right T4s when they file [their taxes]," she said. "So again, it's really important for employees to reach out and let us know if they've been overpaid."