Sir Michael Cullen has earned more than $84k for his part-time work as chair of the Tax Working Group.
The group released its final report on February 21 recommending a capital gains tax be applied to gains from residential rental properties, all land and buildings, business assets, intangible property and shares.
But Cullen has controversially been kept on beyond the report's release to answer queries about the report.
In response to a question from National's finance spokeswoman Amy Adams, finance minister Grant Robertson said Sir Michael Cullen had been paid $84,115.05 as at March 6 2019.
"This includes reimbursement of expenses incurred, as well as appropriate remuneration for the chair's time."