Momentum for imposing GST on items bought overseas is gathering pace.

The working party on the issue is to report in the next few weeks: that work will look at lowering the threshold for GST from the present level of $400.

But while that working party has attracted most of the attention, other more low key efforts are under way to move New Zealand in the same direction.

Included in this work, which is likely to add pressure to the debate, is a set of revisions by Statistics New Zealand to how GDP is calculated.