Senator Pamela Wallin is listed as a resident of Toronto — and not Saskatchewan, the province she represents in the Senate — according to the corporate filings of a Bay Street investment firm.

Wallin, a former Conservative now sitting as an Independent, was named to the board of directors of Gluskin Sheff and Associates in 2006, when it first sold shares to the public. She sat on the board for seven years, earning more than $450,000 in directors' fees and stock payments.

Gluskin Sheff describes itself on its website as a wealth management firm handling portfolios of $3 million or more for high net worth private clients, as well as some institutions and pension plans. It was founded in 1984 by Ira Gluskin and Gerald Sheff.

It’s difficult to determine with certainty how much Wallin was paid to sit on this board, but documents show directors were paid between $500 and $1,500 per meeting, plus an annual retainer of between $40,000 and $50,000. There were also other payments and stock options offered.

Side income in the Senate Like MPs, senators are not prohibited from having outside business interests. Senate rules allow Wallin to serve on corporate boards like Gluskin Sheff and Porter Airlines. However, this outside employment must be disclosed. Senators must also report the source, but not the amount, of any income over $2,000 they receive from these activities.

Wallin never attended more than 10 board or committee meetings per year, the filings show.

CBC News has learned Wallin resigned from the board last month.

Wallin was named to represent Saskatchewan in the Senate by Prime Minister Stephen Harper in 2008.

Senate journals show that when Wallin took her seat in the red chamber in 2009, she was officially summoned as a resident "of Kuroki Beach, in the province of Saskatchewan."

Wallin has owned a summer cottage for years on nearby Fishing Lake, but worked elsewhere for decades — earlier as a well-known broadcaster and later as a diplomat, among other roles.

The Gluskin Sheff corporate filings appear to support that allegation. In each one of seven separate annual filings required by securities regulators, Wallin was officially listed as a resident of Toronto.

Each filing was certified as accurate by the board of directors on which Wallin sat. That means that for the last five years, Wallin asked the Senate to believe she resided in the Prairie province, while down on Bay Street, they thought she lived in Toronto.

Residency rules part of controversy

Wallin now may have new questions to answer as a Senate committee continues its examination of her expenses. Wallin left the Conservative caucus last month as an audit into her travel expenses continues.

The Constitution makes specific demands of those appointed to the Senate – rules that are now up for interpretation in legal opinions sought over the course of the Senate expenses controversy.

Senators are required to own at least $4,000 worth of property in the province they represent. It’s also mandatory that a senator "shall be resident" in that province.

Wallin has not responded to email requests for comment on these latest developments.

In February, when Wallin was still speaking publicly about her expenses and the review she faced, the now former Conservative senator told CBC Radio in Saskatchewan that it was certain that province was her home.

"The question of home is pretty clear to me," she said, "and there’s no disputing that Saskatchewan is my home."

But that issue is not quite so clear to Liberal Senate Leader James Cowan.

"I think she has some explanations to provide," he said in an interview Thursday.

Cowan said if the filings are accurate, then Wallin might never have been eligible to sit in the Senate and collect the $135,000 annual Senate salary.

"I have to be resident in the province of Nova Scotia to be a senator from Nova Scotia," he said. "Senator Wallin would have to be a resident of the province of Saskatchewan.

"Now why she would show Toronto as her residence rather than Saskatchewan, I don’t know."

In addition to her cottage, records show Wallin owns either part, or all, of two homes in Wadena, Sask., the town the former broadcaster grew up in.

But she also owns a condominium off Yonge Street, in Toronto’s tony Rosedale neighbourhood.

The building is described by its managers as "the quintessential upscale, midtown residence."

Multiple homes part of travel expense questions

Sources tell CBC News the audit investigation of Wallin’s living and travel expenses has focused on the preponderance of travel between Ottawa and Toronto.

In the past, Wallin has explained one of the complications with her expenses is the fact that she frequently flies to Toronto for a layover before flying onwards to Saskatchewan.

"If the trip does not originate in Ottawa, then it doesn’t count as a trip to my home province," she said in February.

But Senate sources familiar with the work of independent auditors Deloitte suggest that is only one part of the issue Wallin faces.

They also point out none of the five other senators from Saskatchewan claims to face the same challenge.

One of those five is Conservative David Tkachuk, chair of the Senate's internal economy committee.

On Thursday, he told CBC News that the audit of Wallin’s expenses will not be complete before the Senate is expected to rise at the end of June. The delay raises the prospect of an entire summer passing before the full Senate would be able to vote on any action against Wallin.

Tkachuk said he has yet to receive a definitive answer to when the audit will be complete.

The internal economy committee can continue to sit into the summer, even if the full Senate has risen for a summer break. But it would not be able to table its report until Parliament resumes. It's not clear how, or even if, the committee could make its findings public unless it is able to table a report.

"It's not a mess; it just makes it more difficult," Tkachuk said. "We will deal with it in [the] internal [economy committee] and then we'll table the report as soon as Parliament meets."

That delay may make life less difficult for the subject of the audit.

CBC News has learned Wallin has already repaid over $40,000 of her expense claims. But it's alleged the total payment required could be more than that. A delay could give Wallin more time to prepare.