In the Philippine legal landscape, the security of tenure is a constitutionally guaranteed right. Under the Labor Code, no employee shall be dismissed except for a just or authorized cause and after observance of due process. When an employer fails to meet these standards, the dismissal is deemed "illegal," triggering specific legal remedies and monetary claims.

1. The Two Pillars of a Valid Dismissal

To defend against a claim of illegal dismissal, an employer must prove two elements:

Substantive Due Process: The termination must be based on a valid ground (Just or Authorized Causes).
Procedural Due Process: The "Two-Notice Rule" for just causes (Notice to Explain and Notice of Decision) or the 30-day notice for authorized causes.

2. Primary Remedies for Illegal Dismissal

When a Labor Arbiter finds that an employee was dismissed without valid cause or due process, the law provides for the following primary reliefs:

A. Reinstatement

This is the restoration of the employee to their former position without loss of seniority rights.

Actual Reinstatement: The employee returns to work.
Payroll Reinstatement: If the employer refuses to take the employee back during an appeal, they must at least pay the salary.
Exception: Reinstatement is not required if the relationship has become so strained (the "Strained Relations Principle") that a harmonious working environment is no longer possible. In such cases, separation pay is awarded instead.

B. Full Backwages

Backwages represent the compensation the employee lost from the time of illegal dismissal up to the time of actual reinstatement.

This includes the basic salary, 13th-month pay, and other regular benefits (e.g., allowances, leaves) that would have been earned.
Unlike older rulings, current jurisprudence mandates "full" backwages without deductions for earnings obtained elsewhere during the period of dismissal.

3. Claims for Separation Pay

Separation pay serves two different purposes depending on the context of the case:

As a Substitute for Reinstatement

If reinstatement is no longer feasible due to strained relations or the abolition of the position, the court awards separation pay in lieu of reinstatement. The standard computation is one (1) month salary for every year of service, with a fraction of at least six months being considered as one whole year.

Based on Authorized Causes

If the dismissal was not illegal but was based on Authorized Causes under Article 298 (formerly 283) of the Labor Code, separation pay is mandatory:

Retrenchment, Closure (not due to losses), or Redundancy: One (1) month pay or one (1) month pay for every year of service, whichever is higher (for redundancy); or half (1/2) month pay per year of service (for retrenchment/closure).
Disease: If the employee’s continued employment is prohibited by law or prejudicial to their health, they are entitled to half (1/2) month pay per year of service.

4. Claims for Unpaid Salary and Other Benefits

Regardless of whether the dismissal was legal or illegal, an employee is entitled to all "vested" benefits earned prior to the termination:

Unpaid Salary: Wages for days actually worked prior to dismissal.
Pro-rated 13th Month Pay: Calculated from the start of the calendar year until the date of dismissal.
Service Incentive Leave (SIL): Commutation to cash of unused SIL (5 days per year) for those who have rendered at least one year of service.
Other Company Benefits: Any bonuses or commissions stipulated in the employment contract or Collective Bargaining Agreement (CBA).

5. Moral and Exemplary Damages

These are not automatic. To be awarded damages, the employee must prove:

Moral Damages: That the dismissal was attended by bad faith, fraud, or constituted an act oppressive to labor, causing mental anguish or besmirched reputation.
Exemplary Damages: Awarded if the dismissal was done in a wanton, oppressive, or malevolent manner, to serve as a deterrent for the public good.
Attorney's Fees: Usually 10% of the total monetary award, granted when the employee is forced to litigate to protect their rights.

6. The Burden of Proof and Prescription

Element	Description
Burden of Proof	In illegal dismissal cases, the employer carries the burden to prove that the termination was valid. Failure to do so results in a finding of illegal dismissal.
Prescription Period	An action for illegal dismissal (an injury to rights) must be filed within four (4) years from the time of dismissal. Money claims arising from employer-employee relations prescribe in three (3) years.

7. Illegal Dismissal with Valid Cause (The Agabon Doctrine)

If there was a just cause (e.g., gross misconduct) but the employer failed to follow procedural due process (the two-notice rule), the dismissal is upheld, but the employer is liable to pay Nominal Damages. Usually, this ranges from ₱30,000 to ₱50,000 depending on whether it was a just or authorized cause.