Yes, provided the U.S. customer becomes the actual employer, issues the supporting letter and the accountant holds no ownership in it. The professional duties and the credential are then assessed against the accountant listing.
The paycheque identifies the employer
TN attaches to a U.S. employer or, in some arrangements, a U.S. entity receiving professional services from a Canadian employer. Hypothetical example: the customer will pay the accountant directly, so the customer is the employer for TN purposes and must write the letter. That letter needs the position, the professional duties, the anticipated length of stay and the qualification being relied on. The accountant must not own or control the customer; ownership stakes have to be disclosed because self-employment is outside TN. A second question is whether the fabricator will treat the person as on secondment; if the fabricator keeps paying the salary and bills the customer, the fabricator becomes the employer of record and the letter must be restructured to describe services rendered to the U.S. client. Settle which model the two companies actually intend before the letter is drafted.
Hypothetical example: a Canadian economist is offered a twelve-month forecasting role with a U.S. food distributor. The first review produces a profession-to-duty table: the signed letter assigns demand modelling, price analysis and written forecasts, while the degree and transcript establish the economist's qualification. The record that settles the payer question is the distributor's employment agreement, not an informal promise from its Canadian supplier. If the economist proposes billing clients independently after arrival, the plan changes from prearranged work for the distributor and must be stopped; TN excludes work undertaken on the applicant's own account.