A Somali family who arrived in the country on fake passports and embarked on an asylum fraud have won a battle against deportation.

Hassan Farid Shireh was sponsored by his wife Rahma Mayrane Dimbil to join him in New Zealand after she became a refugee using false information.

But their fraud was uncovered and she fled to Australia, fearing she would be stripped of her citizenship.

They had arrived in New Zealand in 2002 with their four-year-old son on fake Djibouti passports.

Dimbil later claimed asylum as a Somali who had fled Mogadishu in 1990, saying she was at risk of serious harm from his family because they opposed the marriage due to her low caste.

She then sponsored Shireh's re-entry to New Zealand under a different name, but their dual identities came to light after he got his residency.

In 2013, they were sentenced to nine months' home detention and 150 hours of community service for supplying information knowing it to be false or misleading, producing a certificate of identity fraudulently and producing a visitor's visa fraudulently.

Her refugee status was cancelled but her citizenship prevented her from being deported. She later moved to Australia with their daughter, in fear that her citizenship would be revoked if she remained in New Zealand.

A Ministry of Business, Innovation and Employment memo said that seeking to deprive her of her citizenship while she was in Australia could cause difficulties for the Australian authorities by leaving her stateless.

A Deportation Liability Notice was served on her husband last year but his appeal to the Immigration and Protection Tribunal was successful.

It found it was not in the best interests of his three sons, who remained with him when his wife left, for him to be deported, as they would either have to move to Somalia with him or stay without a parent in New Zealand.

"They will leave the first world environment in which they have been raised, where they have friends and where they have educational opportunities available to them," it ruled.

"They would relocate to a comparatively volatile under-developed environment where they will live in poverty, will clearly be perceived as outsiders and where they will have no access to ongoing education of a similar quality to that they have received to date.

"If their mother returned to New Zealand to care for them, she may face proceedings to strip her of her New Zealand citizenship, and she may herself become liable for deportation."

It said none of the children were implicated in their parents' wrongdoing yet the consequences for them of their father's deportation would be profound.

The tribunal heard Shireh heads a Somali trust and, before his convictions, worked as a bilingual tutor and teacher aide for refugee and migrant children.

He was studying for a degree in social work when the charges were laid and had spells in and out of work since he was convicted.