The retail group that owns Rebel Sports, Supercheap Auto and Macpac has admitted to underpaying workers by almost $8 million after incorrectly calculating overtime pay and allowances.

Super Retail Group on Tuesday said it was booking provisions in its full-year accounts of $7.9 million in anticipation of back payments to workers who were underpaid since 2010.

Super Retail Group said it underpaid staff working on its store fit-out team. Credit:Bloomberg

The underpayments, uncovered by an internal review, relate to workers who were either seconded to or worked permanently in its "set-up" team, which fits-out or refurbishes the group's more than 600 stores.

Super Retail said it incorrectly applied time in lieu, penalty rates and allowances to overtime hours.