CIC Quote
The date a person signs the application form is the date of filing. Where the date on an application is more than three months old (90 days) when received (staledated) or where the date is a date into the future (postdated), the application will be treated as if it is unsigned. An unsigned application is not a duly completed application and will be returned to the applicant.
Same application may be used
It is not necessary for the applicant to submit a new application kit every time an application is returned for incompleteness. Unless the application is stale dated, post dated, unsigned or undated, the applicant may update the information on the current kit and re-sign and redate the application.
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Having said that I think it is a good idea now;
1) update/verify the form used is current
2) use updated residency calculator (adding 2/3 months more physical presence)
3) include copy of letter you got from CIC, keep original with you.
4) Attach the new documents CIC has requested.
4) include a covering letter and mention that CIC requested files are attached
3) Call CIC if in doubt.
to reduce the chances of unseen problems again. CIC stamps are fine and ensure agents that those documents were verified earlier. Keep the documents added/changed (reason of return) separate than original documents.