More than 15,000 New Zealand Post workers will be paid for working over time, dating back to 2004, following a Court of Appeal decision.
The Postal Workers Union took the company to court in 2008, arguing it was not paying the correct daily pay, which includes public holidays, sick leave and bereavement leave.
The union's advocate Graeme Clark said New Zealand Post had put aside $11 million to pay the workers.
"Very clear documentation will be provided to everybody to show what they should have been paid, but I think it's still a bit of a mystery to people about how much it will actually be."
Mr Clark said many New Zealand Post employees' work overtime, which will now be reflected in relevant daily pay.