John Key's promise of $3 billion in tax cuts some time in the next few years threatens to make next week's budget "obsolete", Westpac chief economist Dominick Stephens warns.
Finance Minister Bill English is expected to take a conservative approach to the Government finances with an eye on paying down debt and heading back to surplus when he delivers the Budget next Thursday.
But if there are no tax cuts announced "but the plan is to deliver them further down the track then the fiscal accounts laid out next week are not actually relevant," Stephens says.
He argues the capacity of the Government to deliver both tax cuts and pay down debt this decade is limited and possibly based on overly optimistic Treasury forecasts
"Treasury hasn't really taken seriously the downturn associated with the unwind of the Canterbury rebuild." he says.