Introduction to the Cost Allowance Regime in Portugal

In the current Portuguese business landscape, managing travel and representation expenses is a fundamental pillar of administrative and tax efficiency. Cost allowances are not merely salary add-ons but compensation mechanisms for expenses incurred by employees while serving their employer. As of March 27, 2026, with the year-end closing on the horizon, it is imperative for managers and accountants to master the nuances of the IRS and IRC Codes to avoid severe tax contingencies.

The relevance of this topic is heightened by the increasing scrutiny from the Tax and Customs Authority (AT) regarding what it terms "disguised remuneration." Many companies use cost allowances to increase the employee's net income without the corresponding Social Security burden. However, failure to meet formal requirements, such as travel logs, can lead to the tax disregard of these expenses and the application of heavy autonomous taxation rates under Article 88 of the CIRC.

Legal and Conceptual Framework

Cost allowances aim to cover food, accommodation, and transport expenses. To ensure they are not considered employment income (Category A), they must respect the legal limits set annually for the public sector. Otherwise, the excess is taxed under IRS and subject to Social Security contributions, as per Article 2(2)(d) of the CIRS.

Taxation Regime in IRS and Social Security

For the employee, cost allowances are tax-exempt up to the limits fixed for State servants. It is essential to distinguish between national and international travel, as the allowed values differ significantly. In 2026, reference values follow the update trend seen in previous years due to inflation, requiring rigorous administrative control.

Exemption Limits and Calculation Rules

When an employee travels in their own vehicle for work, mileage compensation is a frequently exercised right. The current exemption limit is €0.40 per kilometer. If a company pays, for example, €0.50/km, the €0.10 difference will be considered employment income, subject to withholding tax and Social Security contributions (11% from the employee and 23.75% from the company).

Practical Case 1: Travel in Own Vehicle
A consultant travels 1,200 km in a month to visit clients. The company pays €0.45 per km.
Total value: 1,200 km * €0.45 = €540.00.
Exempt value: 1,200 km * €0.40 = €480.00.
Taxable value: €540.00 - €480.00 = €60.00.
On these €60.00, the company must calculate IRS withholding and TSU (34.75% total), while the €480.00 is received tax-free.

Impact on IRC and Autonomous Taxation

From the company's perspective (IRC taxpayer), the treatment of these expenses is critical for calculating taxable profit. According to Article 23 of the CIRC, only expenses proven necessary for obtaining or guaranteeing taxable income are deductible. However, cost allowances and mileage compensation face an additional limitation: autonomous taxation.

Article 88 of the CIRC: The Tax Penalty

Cost allowances and mileage charges not billed to customers are subject to a 5% autonomous tax rate. This rate applies to the total expense, regardless of whether the company shows a tax profit or loss. If the company reports a tax loss for the year, the autonomous tax rates increase by 10 percentage points, rising to 15%, as per Article 88(14) of the CIRC.

Documentary Requirements: The Itinerary Map

The deductibility of the expense and its exclusion from IRS income depend on the existence of an itinerary map (travel log). According to AT guidelines, this document must include: location, date, reason for travel, vehicle identification, start and end mileage, and the amount paid. The absence of this document leads to total disregard of the expense in IRC and taxation in IRS for the employee.

Common Errors to Avoid

• Lack of Itinerary Maps: The number one mistake. Without logs, the AT assumes the values are hidden salary.
• Payments Above Limits Without Tax: Paying €0.50/km and not processing the excess in the payroll.
• Meal Allowance Duplication: Paying full daily allowance and meal allowance on the same day.
• Invoices in Employee's Name: For cost allowances, the employee receives a fixed amount. If the company wants to deduct direct travel expenses, invoices must have the company's NIF.

Step by Step: How to Implement a Cost Allowance System

1. Define Internal Policy: Set the values to be paid and eligibility conditions in writing.
2. Create Log Templates: Provide Excel files or software for recording dates, destinations, and mileage.
3. Documentary Validation: The financial department must cross-check logs with tolls (Via Verde) and calendars.
4. Payroll Processing: Integrate values into pay slips, clearly distinguishing exempt from taxable portions.

Sources and Legal References

• Article 2 of the Personal Income Tax Code (CIRS).
• Article 23 of the Corporate Income Tax Code (CIRC).
• Article 88 of the Corporate Income Tax Code (CIRC).
• Article 21 of the Value Added Tax Code (CIVA).
• Decree-Law No. 106/98, of April 24 - Legal regime for cost allowances.
• Social Security Contribution Code (Law No. 110/2009).