Remember that work-related expenses reimbursed by the employer to the employee (such as reimbursement of travel expenses, parking tickets, office supplies etc.) must appear on the employee’s tax form 281.10 since the income year 2022 (for filing in 2023). They are considered as tax-free but need to be displayed for transparency and tax evasion prevention reasons.
You can add these amounts every year in December or at the latest by mid-January. This is not about regular allowances that you may already provide and report through the payroll system but one off expenses that you process throughout the year.