A widow fraudulently obtained almost $110,000 from ACC last year, the single biggest sum illegally collected in Northland.
The woman was paid $109,931 of the $444, 674.16 paid out to people in the region making false claims.
She had been financially dependent on her husband and was entitled to the benefit after he died in an accident. But she kept claiming it after she began living with her new partner.
More than $3 million was fraudulently obtained from ACC throughout the country, with Northland's contribution making up 14 per cent.
ACC spokesman Glenn Donovan said there were 21 cases in Northland in 2011 but none ended up in court.
Prosecution of the widow was considered but not pursued.
"The client acknowledged the need to pay the money back to ACC,'' Mr Donovan said.