Kopua had agreed to advise the ministry if there were any changes in her living situation but failed to do so.
Enquiries found she had been living "in a relationship in the nature of marriage" from December 9, 2002 until December 1, 2008, and April 18, 2009 until April 25, 2011.
Kopua had not advised the ministry of these changes and continued to receive the benefit. She had eight times submitted forms falsely stating she was not living with anyone or that she was single.
Kopua was interviewed on September 13, 2011 and said she was aware of her obligations.
She had not owned up to her true circumstances because "she regarded it as a security thing for her children".
Kopua received overpayment of $91,488.55 during the times she was in a relationship.
This was made up from the domestic purposes benefit, unemployment benefit, accommodation supplement, temporary additional support, and the special needs grant.
Judge Denys Barry remanded Kopua to November 8 for sentence.