Short answer. Almost always because the two of you were terminated on different grounds. The Labor Code sets one month per year of service for redundancy or labor-saving devices, but only half a month per year for retrenchment and for closures not caused by serious business losses. Same exit date, different rate.
What the law says
In case of termination due to the installation of labor-saving devices or redundancy, the worker affected thereby shall be entitled to a separation pay equivalent to at least his one (1) month pay or to at least one (1) month pay for every year of service, whichever is higher.
Labor Code, Article 283 — Closure And Personnel Reduction. Read the full provision →
Two different rates, set by the ground
The article creates two tiers, and everything turns on which authorised cause the employer actually invoked. Where the termination is due to the installation of labor-saving devices or redundancy, the worker gets at least one month's pay, or one month's pay for every year of service, whichever is higher. Where it is retrenchment to prevent losses, or a closure or cessation not due to serious business losses or financial reverses, the entitlement drops to one month's pay or at least half a month per year of service, whichever is higher. Two people leaving on the same day under different notices are simply on different sides of that line.
Other reasons the amounts differ honestly
Before assuming an error, check the arithmetic. Length of service is the biggest multiplier: a colleague with eleven years will out-earn one with four on the same rate. The statute also directs that a fraction of at least six months counts as one whole year, which can shift a computation by a full year in one worker's favour and not the other's. Pay rate matters too, since the multiplier is the worker's own monthly pay. And both tiers are floors, not ceilings — they say at least. A collective bargaining agreement, a company policy, or a long-standing practice of paying more is enforceable above the statutory minimum.
When the difference is a red flag
The gap becomes worth questioning where both of you were removed for the same reason but paid at different rates, or where the employer's paperwork does not name a ground at all. Watch for a company that describes the exercise as redundancy in meetings but writes retrenchment in the notice, which halves the rate. Watch also for a closure justified by serious business losses, since that is the position that removes the separation-pay obligation entirely for that ground — and an employer taking it must actually prove the losses with credible financial evidence, not merely announce them. Ask in writing which cause was applied to you and how the figure was computed.
Practical steps and the limits of this rule
Keep the notice served on you, the computation sheet, your payslips, and proof of your start date; these four documents decide most disputes about the amount. Remember that a valid termination under this article also requires written notice to you and to the labour department at least one month before the intended date, and that a shortfall in notice is a separate defect from a shortfall in pay. Do not sign a quitclaim you do not understand. Note finally what this provision does not cover: it does not govern retirement pay, dismissals for just cause, or unpaid wages and benefits, each of which is computed under its own rules.