That meant additional savings of $1.2 million would need to be found from a variety of potential sources.
Mayor Dave Cull said the most likely use of the money saved would be to accelerate the repayment of council debt.
Alternatively, the savings could be used to lower the rates rise for the year to 3 per cent, or use the spare money for a new project, although that was considered unlikely, he said.
The savings goal was "challenging", but staff had responded well to similar challenges to date, he said.
Council chief executive Paul Orders said when contacted debt repayment was "clearly a key issue for councillors", and cost-cutting options were being considered.
"It means the days of growth budgets are over as far as the Dunedin City Council is concerned," he said.
The guidelines were drawn up following a workshop with Mr Cull, his councillors and senior staff on August 9.
They were released to the ODT, following a request under the Local Government Official Information and Meetings Act 1987.
Mr Cull said options identified by staff to achieve the additional savings would be considered when budget meetings began in January.
Mr Cull confirmed that could include cuts to service levels - as the guidelines noted - but councillors would have the final say about whether the price of cuts was too high.
The "general rule" given to staff on capital spending was that no new projects could be added to the 10-year capital spending programme agreed at this year's long-term plan hearings, the guidelines said.