It is a follow-up to the city's earlier Computer Leasing Inquiry, and is investigating three other questionable contracts.
North York's treasurer, Wanda Liczyk, was the sole voice in favour of adopting TMACS for the amalgamated city, and when she subsequently became treasurer of the "megacity", she implemented TMACS without consulting city council.
TMACS was developed for North York's city government by two American software consultants, David Maxson and Michael Saunders.
Testimony before the inquiry has confirmed that from 1989 to 1991, Saunders and Liczyk had a personal romantic relationship.
However, in response to suggestions that she should have declared a conflict of interest and recused herself from such decisions, Liczyk has testified that she is able to separate personal and business matters.