Expiring Port of Entry Letter of Introductions
A Port of Entry (POE) Letter of Introduction is valid for one year after its date of issue. Once a letter is issued under the IEC program, it is considered a participation and cannot be cancelled.
Contact us if your letter expires in the next 30 days, and you cannot travel due to disruptions caused by COVID-19.
You could be eligible for an extension of your current POE letter for up to 12 months.
The length of your extension will depend on whether:
you have already received an extension on your POE letter, and
if applicable, your immigration medical examination on file can be reassessed and extended.
Decisions will be made on a case-by-case basis at the discretion of an immigration officer.
If your letter expires in 60 days or more, please wait until a month before expiry to contact us.
出典元：https://www.canada.ca/en/immigration-refugees-citizenship/services/coronavirus-covid19/iec.html

もし期限が一カ月を切っている場合は、移民局へコンタクトを取り延長したい旨を伝えましょう。それか期限が迫っている方はMyCICアカウントを常に確認することをお勧めします。