Don is a member of Chartered Accountants Australia and New Zealand (CAANZ) and practised as a Chartered Accountant in public practice from 1980 until April 2023. He retired as a Partner in Price Waterhouse in 1996 and specialised in acting for small or medium sized enterprise businesses since then often fulfilling the role of finance director for those companies. Don was the Chairman of listed banking software technology company Finzsoft Solutions Ltd. Don is a previous Chairman of the Board of Directors of the Auckland Cricket Association. He has held a previous public company directorship with Cooks Coffee Company Ltd (previously known as Cooks Global Foods Ltd) as well as directorships with a number of private companies.