The Expatriate Party of New Zealand had wanted to agitate to improve the lot of Kiwis living in Australia, who are denied access to most social services.

But New Zealand's electoral commission has not registered the Expat Party before a cut off this week for new parties to contest the September 20 poll.

That has effectively locked the Expat Party out of the contest, despite attracting well over the required 500 members.

The Expat Party had aimed to win a place in New Zealand's parliament, and from there lobby for fairer access to social services for the estimated 640,000 Kiwis living in Australia.

New Zealanders are allowed to live in Australia, work and are required to pay local taxes, but after a 2001 change are denied the vote or access to social services such as disability support.

The treatment of New Zealanders in Australia has been raised officially as recently as last month.

Grant Cheesman, a leader of the Expat Party, blamed the New Zealand electoral commission for bungling the registration process.

New Zealanders are allowed to vote while living overseas, provided they have returned home in the past three years.

But the Expat Party said the commission had rejected 244 members on the basis they had failed to state when they were last in New Zealand, but this included some who currently live in the country.

A spokeswoman for the commission said the application had been processing with enrolment checks.

But she said the commission was prohibited from registering a party or logo after the day the writ is issued for the election - August 20.

"Given that it is now writ day, we are unable to complete the registration process before the election. The Commission will continue to work with the party after 9 October 2014," she said.

Mr Cheesman said the party would run a candidate, Vicky Rose, as an independent.