The company last year disclosed it had made an error that led to underpayment of minimum wages, overtime, annual leave entitlements and superannuation between 2011 and 2018, and resulted in record-keeping breaches.

Fair Work began investigating the issue after the ombudsman was notified.

Subsequently 407 current and former employees have received a total of $7.44 million in back-pay, with individual amounts ranging from $2593 up to $158,978.

In January, the AustPayroll Association said employees working in middle management, administration, production, technical and engineering roles were affected, including some staff at Benalla, Mulwala and Bendigo.

Inspectors found the underpayments largely occurred because Thales failed to sufficiently check that the salary contracts it entered into with employees were above the minimum salaries listed in enterprise agreements and awards.

IN OTHER NEWS:

Under the undertaking with the ombudsman, Thales must apologise to its employees for underpaying them and implement a new payroll system to improve its wages and record-keeping practices.

It must also have an external auditor conduct audits of employees' pay and conditions later this year and again next year, and report the results to the ombudsman.

Thales will also make a $200,000 payment to the Commonwealth's Consolidated Revenue Fund.

Fair Work Ombudsman Sandra Parker said that the regulator considered an undertaking appropriate after the company back-paid its workers and out significant resources towards overhauling its workplace practices.

"This outcome sends a strong message to employers that if you don't prioritise workplace compliance, you risk underpaying staff on a large scale and facing a massive back-payment bill," Ms Parker said.