The first couples have applied to have their relationships recognised by a civil union after a change in the law came into effect today.

The Civil Unions Bill allows same-sex and heterosexual couples legal standing on a par with marriage.

Registration takes three days so Friday is the earliest the ceremony can be held.

Des Smith and John Joliff, who have been together for 19 years, were first in line at the Internal Affairs office in Wellington to apply for a civil union licence.

Another couple applied early this morning in Christchurch.

Mr Smith and Mr Joliff plan to make a lifetime commitment in a ceremony on Sunday after a street parade.

With couples begining to take advantage of the new law, opponents appear to have accepted defeat.

Destiny New Zealand leader Richard Lewis said there were no plans to disrupt the first civil unions ceremonies, which can be held from Friday.

"It's a case of moving forward and doing what we can to protect the institution of marriage that we still hold very dearly," Mr Lewis said.

Destiny New Zealand is the political arm of the Destiny Church.

Catholic Church spokeswoman Lyndsay Freer also said there had been no special direction to hold prayers or homilies on the issue but emphasised priests would not conduct the ceremonies.

Mr Lewis said the party and church "did what they could" to stop the passing of the bill.

"The reality is come Friday or Saturday when the manifestation of same-sex marriages are evident to all New Zealanders.

"It really changes the face and nature of that dynamic of marriage which is a tragedy for future generations who we want to enjoy marriage for what it is."

Department of Internal Affairs spokesman Tony Wallace said by 9.30am today a couple in Wellington and another in Christchurch had applied for licences at its offices.

It was possible more had applied through courts and local authorities. Mr Wallace said it was difficult to predict demand.

"It's difficult to say because its a completely new issue. We don't know what's going to happen," he said.

Civil union licences cost the same as marriage licences -- $120 -- and people can apply to the Registrar of Births Deaths and Marriages.