The Taxpayers' Union believes Otago residents deserve to know why former Chief Executive of Delta, Grady Cameron received a payout of nearly a million dollars.

The union's Executive Director Jordan Williams says Delta and its former CEO should reveal the reasons for the payout.

Grady Cameron resigned earlier this year and the organisation is refusing to give details of the pay-out, citing a confidentiality agreement.

The Taxpayers Union says where Delta is a council owned company, ratepayers have a right to know.