Finance Minister Bill English has rejected criticism that he failed to protect taxpayer interests when the Crown retail deposit guarantee scheme was set up.
An Auditor-General's report has found the Treasury could have done more to minimise a $1.9 billion loss for taxpayers from bailouts of finance companies covered by the scheme.
Labour set up the guarantee just before the 2008 election, but finance spokesperson David Cunliffe says the buck stops with Mr English.
Mr English says the scheme was set up in a hurry during the election campaign by necessity.
At the time, he says, no one understood the vulnerabilities of companies such as South Canterbury Finance, which subsequently collapsed.
The report says the scheme achieved its goal, as no banks failed, but the Treasury had no coherent strategic overview.
Mr Cunliffe says it raises disturbing questions about the quality of governance and oversight.
The Crown has had to pay about $2 billion to depositors and is expected to recover only $0.9 billion of that.
David Tripe of the centre for banking studies at Massey University, says there are important lessons to be learned from the way the scheme was implemented.
He says the biggest problem was its implementation without adequate planning.
Dr Tripe warns new situations are developing which New Zealand may also not be adequately prepared for, including a deposit insurance scheme about to come into effect in Australia.
With the guarantee effectively ended, he says, investors and depositors may start looking to move offshore where guarantees remain available.
Council of Trade Unions economist Bill Rosenberg agrees both the Treasury and the minister could have done more in terms of planning and monitoring.
He says when the guarantee was set up, the fear was that if institutions such as finance companies were not included, depositors would simply pull out and cause them to crash.