Two weeks before US trade officials are set to rule on a case against Bombardier, the Canadian government has filed a complaint against the USA with the World Trade Organisation.
The complaint, dated 10 January, raises issues with US processes related to imposing and collecting countervailing and anti-dumping import duties – the same taxes the US Department of Commerce has slapped on Bombardier's CSeries.
The document specifically faults the USA for not reducing anti-dumping and countervailing duties when those duties exceed "WTO-consistent rates".
Canada also faults the USA for placing controls on so-called "input products that are used or incorporated into a product under investigation".
Canada's complaint comes as Bombardier proposes to skirt potential import duties by opening a CSeries assembly plant in Alabama. Though that plan would not see a fully-assembled CSeries cross the US-Canada border, Bombardier would need to import major CSeries components into the USA.
Bombardier, which did not immediately respond to questions about Canada's WTO filing, has insisted that imports of CSeries' components would not be subject to import duties.
Boeing, however, says the taxes would be levied on components.
At the end of January, the ITC is scheduled to make a final ruling about whether Bombardier's sale of CSeries to Delta Air Lines in 2016 caused harm to US industry – namely Boeing.
The ITC's determination remains the last step in a process started in April when Boeing complained to the US Department of Commerce that Bombardier violated trade laws by selling the heavily-subsidised aircraft at below-cost prices.
Bombardier has denied the claims.
The Commerce Department in December sided with Boeing, ordering that CSeries be subject to a 292% import duty.
The duty, however, will be imposed only if the ITC find Boeing suffered harm.
On 9 January, the ITC asked Bombardier to provide more information about the structure of the company the manufactures the CSeries and about renegotiations between Bombardier and customer Delta Air Lines.
Bombardier has until 16 January to respond.
News broke in December 2017 that Delta and Bombardier were negotiating delivery details related to Delta's CSeries purchase.
A Delta executive said the airline wanted Bombardier to guarantee that all the aircraft it ordered will be built in Alabama.