Geoff explains the issue very well and has the numbers right. You can verify for yourself that the Government intends to use the surplus units to allow greenhouse gas emissions to increase out to 2020 while claiming that New Zealand is 'meeting' it's "minus 5%" emission reduction target. Just go to Latest update on New Zealand's 2020 net position on the Ministry for the Environment's website.
That webpage states explicitly that New Zealand will have 85.7 million emission units surplus after using some to meet the 2020 target. Here is a screenshot.
Further down the page is this barchart that shows that New Zealand's gross emissions from 2013 to 2020 are expected to be 655.9 million tonnes and that the baseline is 509.8 million tonnes.