He said advice from Treasury and the Reserve Bank had been taken on the matter.
Robertson said the Government planned to "tilt the balance" toward first home buyers and wanted to incentivise new builds.
"As the Prime Minister has outlined, we will also make more announcements on the supply side as Budget 2021 is finalised. These will build on the Government's housing programme that has seen us build more houses than any government since the 1970s.
"Anyone who tries to tell you that there is a single silver bullet for addressing the housing crisis is not facing reality - or is speaking from the safety of Opposition.
Robertson said Budget 2021 would also focus on keeping Covid-19 out of the country, continuing to recover from the lockdown, climate change and child poverty.
He also indicated targeted, prioritised spending.
"The significant resources we have put into the recovery and rebuild will be supplemented by further investment over coming Budgets, but quite clearly we need to strike a balance with rebuilding and maintaining a strong fiscal position.
"This includes rigorously assessing all of the spending that was provided for in the Covid Response and Recovery Fund. As the economy has rebounded stronger-than-expected, we are taking the opportunity to assess if money can be better targeted or reprioritised where it has not already been used."
Wellbeing objectives for the budget included lifting Māori and Pacific incomes, skills and opportunities, and combating the impacts of the pandemic.