"The existing regime can be seen as a form of tariff on trans-Tasman investment flows" which leads to the inefficient allocation of resources, the report said.
"Trans-Tasman investment decisions are being made at least in part to minimise tax payments, rather than on a purely economic basis," it said.
If mutual recognition of the tax credits was introduced the study estimates household consumption would increase by $7 billion by 2030, with larger gains in Australia due to its higher level of tax.
The study was commissioned by the Australia New Zealand Leadership Forum and Business New Zealand, and is part of each group's submissions to the joint investigation by Australia and New Zealand's respective Productivity Commissions into improving the Closer Economic Relations pact.
The Productivity Commissions' draft report is expected to be released on September 18, with a final report flagged before the end of the year.
Since 2009, New Zealand and Australia have been trying to accelerate the creation of a single economic market by aligning a range of areas in business law.