Subparagraph 152(4)(a)(i) of the Income Tax Act provides that the Minister (CRA) may make an assessment, reassessment or additional assessment beyond the normal reassessment period where the taxpayer has made a misrepresentation that is attributable to neglect, carelessness or willful default or has committed any fraud in filing the return or in supplying any information under this Act. Whether the failure to file a return of income is attributable to neglect, carelessness or willful default will depend on the particular facts.
Generally, the CRA will not issue an arbitrary assessment without first requesting the taxpayer file a return. Therefore it is likely that the taxpayer would have been aware of the request to file, therefore, in these circumstances, misrepresentation is attributable to neglect.
The onus is on CRA to establish you knowingly failed to comply with your tax obligations.
As per the ITA.
Assessment and reassessment
(4) The Minister may at any time make an assessment, reassessment or additional assessment of tax for a taxation year, interest or penalties, if any, payable under this Part by a taxpayer or notify in writing any person by whom a return of income for a taxation year has been filed that no tax is payable for the year, except that an assessment, reassessment or additional assessment may be made after the taxpayer’s normal reassessment period in respect of the year only if
(a) the taxpayer or person filing the return
o(i) has made any misrepresentation that is attributable to neglect, carelessness or wilful default or has committed any fraud in filing the return or in supplying any information under this Act, or
o(ii) has filed with the Minister a waiver in prescribed form within the normal reassessment period for the taxpayer in respect of the year;
(b) the assessment, reassessment or additional assessment is made before the day that is 3 years after the end of the normal reassessment period for the taxpayer in respect of the year and
o(i) is required under subsection (6) or (6.1), or would be so required if the taxpayer had claimed an amount by filing the prescribed form referred to in the subsection on or before the day referred to in the subsection,
o(ii) is made as a consequence of the assessment or reassessment pursuant to this paragraph or subsection 152(6) of tax payable by another taxpayer,
o(iii) is made as a consequence of a transaction involving the taxpayer and a non-resident person with whom the taxpayer was not dealing at arm’s length,
o(iii.1) is made, if the taxpayer is non-resident and carries on a business in Canada, as a consequence of
§(A) an allocation by the taxpayer of revenues or expenses as amounts in respect of the Canadian business (other than revenues and expenses that relate solely to the Canadian business, that are recorded in the books of account of the Canadian business, and the documentation in support of which is kept in Canada), or
§(B) a notional transaction between the taxpayer and its Canadian business, where the transaction is recognized for the purposes of the computation of an amount under this Act or an applicable tax treaty.
o(iv) is made as a consequence of a payment or reimbursement of any income or profits tax to or by the government of a country other than Canada or a government of a state, province or other political subdivision of any such country,
o(v) is made as a consequence of a reduction under subsection 66(12.73) of an amount purported to be renounced under section 66,
o(vi) is made in order to give effect to the application of subsection 118.1(15) or 118.1(16), or
o(vii) is made to give effect to the application of any of sections 94, 94.1 and 94.2;
(b.1) an information return described in subsection 237.1(7) or 237.3(2) that is required to be filed in respect of a deduction or claim made by the taxpayer in relation to a tax shelter, or in respect of a tax benefit (as defined in subsection 245(1)) to the taxpayer from an avoidance transaction (as defined in subsection 245(3)), is not filed as and when required, and the assessment, reassessment or additional assessment is made before the day that is three years after the day on which the information return is filed;
(b.2) the assessment, reassessment or additional assessment is made before the day that is three years after the end of the normal reassessment period for the taxpayer in respect of the year and if
o(i) the taxpayer, or a partnership of which the taxpayer is a member, has failed to file for the year a prescribed form as and when required under subsection 233.3(3) or to report on the prescribed form the information required in respect of a specified foreign property (as defined in subsection 233.3(1)) held by the taxpayer at any time during the year, and
o(ii) the taxpayer has failed to report, in the return of income for the year, an amount in respect of a specified foreign property that is required to be included in computing the taxpayer’s income for the year;
(c) the taxpayer or person filing the return of income has filed with the Minister a waiver in prescribed form within the additional three-year period referred to in paragraph (b) or (b.1);
(c.1) the taxpayer or person filing the return of income has filed with the Minister a waiver in prescribed form within the additional three-year period referred to in paragraph (b.2); or
(d) as a consequence of a change in the allocation of the taxpayer’s taxable income earned in a province as determined under the law of a province that provides rules similar to those prescribed for the purposes of section 124, an assessment, reassessment or additional assessment of tax for a taxation year payable by a corporation under a law of a province that imposes on the corporation a tax similar to the tax imposed under this Part (in this paragraph referred to as a “provincial reassessment”) is made, and as a consequence of the provincial reassessment, an assessment, reassessment or additional assessment is made on or before the day that is one year after the later of
o(i) the day on which the Minister is advised of the provincial reassessment, and
o(ii) the day that is 90 days after the day of sending of a notice of the provincial reassessment.