As a rule, an objection to a notice of assessment or a notice of determination must be filed within 90 days of the date shown on the notice.
In terms of Canada Revenue Agency:
Filing deadlines – If you are an individual (other than a trust) or filing for a graduated rate estate for the year, the time limit for filing an objection is the latest of the following two dates: one year after the date of the return's filing due date for the year; or 90 days after the day we sent the notice of assessment or determination. In any other case, you have to file an objection within 90 days of the day we sent the notice of assessment or determination.
In terms of Revenue Quebec:
It may be to an individual’s or a testamentary trust’s advantage to file an objection after the 90 days provided for above. An individual or trust may file an objection within one year after the filing-due date (within the meaning of section 1 of the Taxation Act) for the taxation year, where the objection is to:
an assessment under the Taxation Act;
a premium relating to the eligible wages of a person to whom section 51 of the Act respecting parental insurance applies, to the business income of a self-employed worker or to the eligible remuneration of a person responsible for a family-type resource or an intermediate resource, issued under chapter IV of that Act.
an assessment under sections 220.2 to 220.13 of the Act respecting municipal taxation;
an assessment issued pursuant to section 83 of the Act respecting the legal publicity of enterprises;
an assessment relating to an amount payable under section 34.1.1, 37.6 or 37.17 of the Act respecting the Régie de l’assurance maladie du Québec;
an assessment relating to self-employed earnings or earnings as a person responsible for a family-type resource or an intermediate resource under the Act respecting the Québec Pension Plan;
an assessment under sections 358 to 360 of the Act respecting the Québec sales tax.