Up to 6,000 current and former employees of Blackwoods, Workwear Group, Coregas and Greencap underpaid since 2010

This article is more than 11 months old

This article is more than 11 months old

Up to 6,000 current and former employees at Wesfarmers’ industrial division were underpaid an estimated $15m, Guardian Australia has learned.

The head of Wesfarmers industrial division, David Baxby, wrote to staff on Tuesday morning, following inquiries from Guardian Australia last week, to inform them that an internal review had found staff had been underpaid going back as far as 2010.

At least 2,000 current and 4,000 former staff of Blackwoods, Workwear Group, Coregas and Greencap were all underpaid in what the company has said was an inadvertent error.

The error was only discovered when the industrial division went to upgrade to a new payroll system as part of the move to one-touch payroll. Wesfarmers said the error mostly related to entitlements and car expenses.

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The company has estimated almost half of the $15m owed to workers is superannuation on loadings and allowances.

“These were inadvertent errors but they are deeply regrettable and we apologise sincerely and unreservedly to our team members who have been affected over a number of years,” Baxby said.

PricewaterhouseCoopers was brought in to review the extent of the underpayments and Baxby said the fair work ombudsman had been informed as part of the process.

The company was aiming to pay the money owed to workers as quickly as possible, Baxby said.

“Our priority is to back pay all affected team members as quickly as possible, including interest, to ensure affected team members are fully compensated,” Baxby said. “We are also investing heavily in our payroll system, processes and capabilities to fix this issue and ensure it cannot happen again.”

The fair work ombudsman, Sandra Parker, said she would be holding Wesfarmers to account.

“Each week, another large company is publicly admitting that they failed to ensure staff are receiving their lawful entitlements,” she said. “This simply is not good enough.

“Companies will be held accountable for breaching workplace laws. Companies and their boards are on notice that we will consider the full range of enforcement options available under the Fair Work Act, including litigation where appropriate.”

It is the second underpayments report from Wesfarmers in the past week, after the company’s hardware retailer Bunnings reported last week that it had underpaid superannuation for its 40,000 employees.

Wesfarmers confirmed the industrial division underpayment was larger than the Bunnings underpayment, because most Bunnings staff were underpaid less than $200 in total.

Guardian Australia reported in July that members of senior management, including the chief executive and chief financial officer at Blackwoods, had left the organisation, but at the time it was played down by Wesfarmers as “not unusual” and part of a restructure of the organisation.

Wesfarmers said the issue was unrelated.