" A commissioned sales employee can make deductions from her or his employment income only if the type of expense is specified under section 8 of the Act. Each subsection stipulates that the employee must be required by her or his employer, under a contract of employment, to pay for the expenses in the year in the course of her or his employment.
" Paragraph 8(1)(f) authorizes the deduction of expenses up to the limit of commission income earned. In addition to those conditions, the amounts must be expended by the employee in the year for the purpose of earning income from employment, and the employee must also:
(a) be employed in the year in connection with the selling of property or negotiating contracts for her or his employer;
(b) ordinarily be required to carry on duties of the employment away from the employer’s place of business;
(c) be remunerated, in whole or in part, by commissions; and
(d) not be in receipt of a non-taxable travel allowance.
" A specified expense will only qualify as a deduction if the above conditions are met and the expense was:
(a) not an outlay, loss or replacement of capital or payment on account of capital;
(b) not an outlay or expense that is not deductible pursuant to paragraph 18(1)(l);
(c) not an amount described in subparagraph 8(1)(f)(vii) in connection with standby charges for a vehicle; and
(d) reasonable in the circumstances."
Justice Lyons added an important caution that applies to both employment and business expense claims:
" Claims for a large number of personal expenses can cast doubt on claims for expenses by a taxpayer. In Chrabalowski v Canada, 2004 TCC 644 (CanLII),  1 CTC 2054, the taxpayer had produced a large number of disorganized receipts for advertising, entertainment, vehicle, parking and supplies, with many unproved implausible and unreasonable claims. Similar to that case and the Court’s finding, Mr. Perera was required to keep proper records and separate receipts but failed to do so making it difficult to differentiate between personal versus employment-related expenses." [My underlining and bold.]
CRA had assessed Mr. Perera a late-filing penalty also. (His return was 8 days late.) J. Lyons exonerated him because he was ill and records showed he was on long-term disability at the time, due to a mental illness:
" This Court has recognized a due diligence defence for the imposition of penalties if a taxpayer demonstrates that reasonable steps were taken to comply with the legislation. In Rupprecht v Canada, reflex, 2007 TCC 191,  TCJ No. 586 (QL), the Court noted, at paragraph 24, that in Bennett v The Queen, the Court held that a due diligence defence is available to a taxpayer against whom a late filing penalty has been assessed but a high degree of diligence is to be expected from a taxpayer. More recently, the Court reiterated the availability of a due diligence defence where reasonable steps are taken to comply with the legislation.
" I am satisfied that given Mr. Perera’s illness, he took reasonable steps and was duly diligent in attempting to comply with the obligation to file his 2010 return. I conclude it would be unreasonable to impose a late filing penalty."
See Perera v. The Queen, 2014 TCC (Lyons)