The secretive, multi-party Board of Internal Economy, which polices House of Commons spending, has sent bills to 68 MPs, including several who no longer sit as New Democrats, ordering them to personally repay the money.
The board ruled last August that the MPs had inappropriately used their House of Commons budgets to pay for 28 employees in satellite party offices in Quebec City, Montreal and Toronto.
On average, sources say the MPs are being asked to pay back about $30,000.
But for some MPs the tab is more than $100,000; sources say the leader's office is being asked to reimburse about $400,000.
The NDP is challenging the board's ruling on the satellite offices in Federal Court, as well as an earlier ruling that found New Democrat MPs had wrongly used $1.17 million worth of free parliamentary mailing privileges to paper 26 ridings with almost 2 million partisan missives.
In the case of the mailings, the board ordered the MPs to repay $36,000 to the Commons and urged Canada Post to recover the rest.
It emerged Tuesday that lawyers for the board and the NDP have been discussing the possibility of an out-of-court settlement of both matters and jointly asked the court last November to suspend proceedings pending further negotiations.
Those negotiations are still in progress.
The NDP maintains its MPs have done nothing wrong and that both decisions are the result of a partisan gang-up by Conservatives and Liberals on the board.
"NDP parliamentary staff have always performed parliamentary duties," NDP House leader Peter Julian said in a statement late Tuesday, referring to the board as a "kangaroo court."
"No evidence to the contrary has ever been provided by our Liberal and Conservative opponents who are acting as judge, jury and executioner against all principles of natural justice."
News that the board has sent bills to more than five dozen MPs was first revealed late Tuesday in a bizarrely worded statement from NDP whip Nycole Turmel, who is the authorized spokesperson for the board. She is also one of the MPs who's been ordered to repay money for the satellite office scheme.
Her statement noted that none of the MPs or satellite office employees has been heard by the board. Moreover, she said "multiple errors have been identified in the (dollar) amounts cited."
"The goal of today's decision is to create leverage against the MPs cited" by the board, she asserted.
A later statement from Andrew Scheer, Speaker of the Commons and chair of the board, identified the number of MPs involved in the satellite office scheme and the total amount owed. It made no such references to errors, lack of due process or the board's motivation.
"Since members (of Parliament) are responsible for the use of House resources, they bear sole responsibility for any inappropriate use," Scheer said.
Should New Democrat MPs lose the court challenge and still refuse to pay, the board can order a garnishee of their salaries.