The Government's plan to ban merchant surcharges remains National Party policy but faces uncertainty over timing as coalition partners withdraw support.

Commerce Minister Cameron Brewer said the ban is a matter of timing as the Government examines whether merchants have passed on the benefit of two Commerce Commission interchange fee reductions. The Government continues to work with the Commerce Commission, MBIE, and Parliament members on the proposal.

"The policy and the view of the National Party caucus is to ban merchant surcharges. That policy hasn't changed, that view hasn't changed, and it's a case of timing," Brewer said.

Coalition partner ACT has withdrawn its support for the ban, while NZ First believes the plan is going nowhere. The Greens do not support the ban in its current form, and Labour has not guaranteed support and has put forward amendments and alternative proposals.

The Retail Payment System Amendment Bill reached an impasse in February. ACT leader David Seymour announced in March that his party had withdrawn support and proposed a counter-proposal. Parliament has approximately 20 days remaining in the legislative timetable.

"We continue to do the work because when we act, we want to make sure that it gets the desired outcome … We don't want it to have an inflationary outcome, for example," Brewer said.

Finance Minister Nicola Willis stated in June that the Government still intended to eliminate PayWave fees. Brewer assumed the commerce and consumer affairs role from Scott Simpson and took on responsibility for the Bill, which Simpson first announced in July last year with expected implementation by May this year.