Question: I entered the U.S. recently for a 4 month period under TN visa status. Will this 4 month period be used as a visit for the purposes of the 6 month visit rule where nonimmigrants can only visit the US for 6 months out of the year?
Reply: I assume you are referring to the 6 month period of admission associated with B-2 visitors (for tourism/pleasure). Technically, except for H-1Bs and L-1s, time spent in one non-immigrant category (e.g. TN visa status) does not count against potential time permitted under another nonimmigrant category (e.g. B1/B2). But you may still be called upon by USCBP to prove that you qualify for B-2 status.
In most cases, Canadian citizens cross the border into the U.S. with a simple verbal explanation of their visit. No I-94 card is issued to formally document the length of the proposed visit. If the purpose of the visit is suitable for a B-1 or B-2 visit, CBP allows the entry without complication or requesting documentation. For an individual who has recently been in the U.S., or who has had prior immigration issues, the inspecting officer may refer the person to secondary inspection. Here the officer may request proof that the individual qualifies for a B-1 or B-2 visit.
For a B-2 visit following recent employment in the U.S. under TN visa status, you may have to show proof that you (1) have resumed your residence in Canada; (2) are now employed in Canada; (3) are only entering the U.S. temporarily; and (4) are visiting only for tourism or to visit with friends or relatives and not working. While there is no specific provision for CBP to limit a B-2 visit based on a recent stay under TN visa status, if there are other concerns about the visit, the inspector may issue you an I-94 card specifically limiting your B-2 visit to 6 months or less.