Money paid to an employee by an employer is typically referred to as remuneration; you need to report remuneration via a T4 slip for each employee who received remuneration if:
You had to deduct CCP/QPP contributions, EI premiums, PPIP premiums, or income tax from the remuneration, or
The remuneration was greater than $500.
What remuneration counts?
The kinds of remuneration that you might pay to an individual that would require a T4 include:
salary
wages (including pay in lieu of termination notice)
tips
gratuities
any vacation pay
commissions
taxable benefits or allowances (such as a gasoline allowance)
retiring allowances
deductions withheld during the year
pension adjustment amounts for employees who accrued a benefit under your registered pension plan or deferred profit sharing plan
the gross and insurable earnings of self-employed fishers
Of note:
You must complete a T4 for all individuals with taxable group term life insurance benefits, even if they received less than $500 in remuneration from you in that year.