The Government says the economy's grown faster than expected so there's a bit more money in the kitty.

Labour's Budget plan has been compared with its campaign fiscal plan and things aren't quite tracking how the party had planned.

Analysis by the Herald has found Crown spending will be almost 12.5 billion dollars higher over five years, than Labour forecast.

Finance Minister Grant Robertson says told Mike Hosking the Government's also managed to re-prioritise spending so there's more money available.

"That was effectively a draft budget based on last year's numbers, what we've now got is a budget based on this year's numbers and the good news is we continue to be able to run a surplus and pay down debt and do the investments we're making."

LISTEN ABOVE: GRANT ROBERTSON SPEAKS TO MIKE HOSKING