Day trips do not count as days absent, correct.jazibkg said:
Day trips do not need to be declared in residency calculation submitted with the application, that's true.
Applicants issued RQ, however, are required to declare all day trips.
And as bambino notes, there are various ways in which a reviewing CIC officer or interviewer might take notice of POE events not reflected in the residency calculation and have questions, which for some may be readily addressed and resolved, but for others this may lead to elevated scrutiny, request for additional documents, even RQ . . . despite the fact that these additional events (be they reflected by stamps in travel documents, or recorded entries noted in the CBSA travel history) were attendant a day trip. This is one of those areas where CIC has left open a pitfall which has tripped up more than a few applicants (mostly resulting in processing delays, additionally intrusive requests for information and documentation, some inconvenience, even if not usually a result as severe as a denial).
These highlight the reasons I personally elected to mention the number of day trips I made each year in my residency calculation; I did not declare all day trips, just one for each year, and in that declaration noted, in the reasons box, how many other day trips I made that year.
This is just one example, however, of some of the nooks and crannies, the nuances, in the way CIC approaches assessing individual applicants, which can indeed catch some applicants unaware and exposed. The CIC citizenship residency calculation FAQs explicitly say, for example, that day trips do not need to be declared, and yet CIC will demand some applicants do declare all day trips. This borders on entrapment.