Metiria Turei has confirmed her mother was a flatmate for part of the period she claimed the benefit.
Turei has also admitted to enrolling to vote at the same address as her baby's father - despite not living there - so she could vote for a friend who was a candidate in Mt Albert in 1993.
The MP made the admission in a statement last night, after Newshub published information from the habitation index that showed Turei listed at the same address as her daughter's father, Paul Hartley, in 1993 and 1994.
The index also showed that in 1996 and 1998 Turei was listed at the same address as her mother.
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 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 where you did not live was an offence under the Electoral Act. Time limits for enforcement meant it would be too late to prosecute, Edgeler said, and the offence was not serious.
Turei met yesterday with 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.
Turei was on a benefit from 1993 until late 1998. She started law school in 1995.