Campaign chairman Steven Joyce said New Zealand's tax system was broad-based and fair, and there was no need to bring farmers into the ETS "when no other farmers worldwide are included".
"Labour needs to front up and be honest about its tax agenda. It's quite obvious they have one and they don't want to talk about it."
The Labour Party has promised a royalty on water if it is in Government, saying users in rural areas would pay around 2c per 1000 litres and the money would be given to councils and iwi to restore waterways. The charge would be set after consultation with industry and iwi.
Labour's policy in 2011 and 2014 to introduce a capital gains tax was replaced by former leader Andrew Little with the promise of a tax working group to look at the whole tax issue but to seek a mandate for any changes at the 2020 election.
Ardern has kept the tax working group but wants to implement changes without seeking a mandate - saying the housing crisis that has taken place under National means waiting until the next election to take action would be too long.
Labour has proposed a regional fuel tax in Auckland to help pay for improvements to the transport network, particularly in rail and including light rail to the airport.
New Zealand First leader Winston Peters has declared he will not support a Labour Government unless Ardern reveals what taxes will be introduced, and continued his criticism of Labour over its tax policy while campaigning in Whangamata today.