The Government is facing the threat of a hole in its tax plan. 

Its promised relief on the back-pocket is meant to be partially paid for with a levy on online gambling - bringing in more than $730 million over four years.  

But the Inland Revenue Department has crunched the numbers... and figures it will only bring in $155 million.  

Revenue Minister Simon Watts told Heather du Plessis-Allan those calculations are correct. 

He says there are a number of mechanisms which will come into play - including the reduction of costs in the public sector which will help balance the books. 

LISTEN ABOVE