Hello mumbai1985 & other member who posted a comment about not ticking tax years:
Situations like yours should not be a valid reason for them to simply return forms back to you .... things like not signing application or date on form & date on physical presence calculator makes sense to return forms.
In your cases they would simply understand the matter if not will ask you to send a clarification or to confirm that info ....as a fellow member I think you should not do any right away .... I wish you all who are in such situations to have them processed .... not to be returned
After IRCC receives the application package, the first step is to do a completeness check. There are undoubtedly specific criteria employed in conducting this check. We do not know what the criteria is, in particular, but some elements are obvious, such as those you mention, like the absence of a necessary signature. From past reports, we know that applications have been returned as incomplete because the applicant did not include proper proof of language ability. IRCC online information has long cautioned that gaps in work or address history could result in the application being returned. Photos not meeting specifications has been a reason why applications have been returned as incomplete.
In any event, the completeness check is largely a mechanical process, in effect checking off the completeness-check script boxes, little or no judgment calls.
Whether what should appear to be an obvious error in the work or address history dates constitutes a "gap" that will trigger returning the application is uncertain, and may depend on how complete the history is otherwise, that is, the extent to which it might appear to be without gaps.
As I noted in another topic, the failure to check off yes or no in the required-to-file column (for tax obligation compliance item) is not a big mistake if, for those tax years, the applicant checked "yes-filed." Indeed, as long as the applicant checked off "yes-filed" for at least three years, that meets the tax-filing obligation qualifications. But here too, what will be deemed an incomplete application is a matter of what criteria those doing that screening use. Nothing the applicant can do but wait to see if the application is returned or there is AOR for it.
AOR means the application has passed the completeness screening. IRCC then enters the application into GCMS and commences the in-process procedures.
Until there is AOR there is no practical way to supplement the application. There is no point trying to communicate with IRCC about the application until AOR.