What would you do with $12 million?

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It's something Auckland woman Savana Taihia never in her dreams thought she'd have to contemplate.

But that's how much money she woke up to after our tax-gatherers mistakenly dumped it into her bank account.

Inland Revenue has admitted to 1 NEWS it was a mistake, and caused by human error last week.

But it's Ms Taihia's treatment after she went to ask her bank what happened to her account that's caused her the most stress.

She told 1 NEWS that ANZ froze her access to her own account while it put her under investigation for a deposit she had nothing to do with.

"When I went to the bank they said I'm going to get investigated, then when I rang to see if my [own] funds got through they said they can't tell me anything," Ms Taihia told 1 NEWS.

Her cousin Donielle Rewha, says both IRD and ANZ should have been much more forthcoming with information.

"ANZ wouldn't say anything to us, it wouldn't answer why it blocked Savana from her own money.

"I just think she's suffering for someone else's mistakes," Ms Rewha said.

She said Ms Taihia was having to get rides and loans just to get to work, because she couldn't access her own money while her account was being investigated.

The minister responsible for IRD, Stuart Nash, has been looking for answers.

His office says he asked the Commission of Inland Revenue for more information and it's a matter he's taking "very seriously".

The Commissioner has given the minister an "assurance that steps are being taken to prevent a recurrence".

Initially Savana Taihia and Donielle Rewha thought the bank account said $12,000 extra was for some reason in the account.

If they hadn't had gone to the bank to ask questions, it seems nobody would ever have known otherwise.