The federal government’s plan to tax unrealised gains in big superannuation accounts could financially decimate farmers who “eke out a living”, says former bank chief Mike Hirst.

Mr Hirst, a non-executive director at AMP and former CEO of Bendigo and Adelaide Bank, said he had no qualms about Labor’s move to double the tax rate to 30 per cent from per cent for earnings on $3 million-plus super funds. But he said there is a difference between assets and earnings.