Major electricity users claim Meridian has 'outperformed' supermarkets and petrol retailers for its level of profit-making.
The finance minister said 400,000 jobs are being covered by the latest round of government support with $484.4m paid out.
Reserve Bank deputy governor Geoff Bascand said keeping the programme to provide up to $28 billion in cheap funding to lenders goes to the central bank's credibility.
Changes to the ETS could allow carbon prices to rise from $50 to $110 by 2026.