Green Party co-leader Metiria Turei once enrolled at an address where she did not live so she could vote for a friend.
The MP enrolled at the address where her baby's father lived so she could vote for a friend who was a candidate in Mt Albert in 1993.
An electoral law expert says enrolling to vote at an address you do not live at is an offence.
Turei has also tonight confirmed her mother was a flatmate for part of the period she claimed the benefit in the 1990s.
The MP made the admissions in a statement tonight, after Newshub published information from the habitation index that showed Turei listed at the same address as her daughter's father, Paul Hartley, in both 1993 and 1994.
The index also showed that in 1996 and 1998 Turei was listed at the same address as her mother.
In her statement, Turei said she did not live at the same address as Hartley.
"I was, however, enrolled to vote at the same address as him, which was in the Mt Albert electorate. A friend of mine was running as a candidate in Mt Albert in 1993, and I wished to vote for them. That was a mistake - one of many I, like many other people, made as a young person."
Turei would not have been eligible for the domestic purposes benefit she was receiving if she did live with her baby's father.
She confirmed that her mother was her flatmate for a period during the mid-1990s, but said they were financially independent while living together in the same home.
"I was the sole provider for my daughter. I was fully financially responsible for us both."
Electoral law expert Graeme Edgeler said enrolling to vote at an address you do not live at is an offence. Time limits for enforcement means it would be too late to prosecute, Edgeler said, and the offence was not a particularly serious one.
Turei today met with fraud investigators at the Ministry of Social Development, after her bombshell admission last month that while at law school as a solo mother she didn't tell Work and Income how many flatmates she lived with, because her benefit would be cut.
She has said she will pay an overpayment back.
Turei was on a benefit from 1993 until late 1998. She started law school in 1995.
In her speech at the Green Party's annual conference earlier this month Turei said she and her baby lived in five different flats with various people while she was at law school as a solo mother.
In three of those flats she had extra flatmates who paid rent, but she didn't tell WINZ about them because her benefit would be cut.
Turei's statement does not make clear if she lived with her mother during the periods in which she was misleading WINZ about the number of flatmates she had. The Herald has contacted her for clarification.
Last month in an interview with the Herald, Turei refused to say whether one of the flatmates she failed to tell Work and Income about was a boyfriend - saying the state has no right to investigate a woman's intimate personal life.
Currently a person stops being eligible for sole parent support if they are in a relationship.
Green Party policy is for a person on a sole parent support benefit to lose eligibility when they marry or enter a civil union, or when they are judged to be in a de facto relationship under the Property (Relationships) Act. That legislation covers couples in a de facto relationship for at least three years.