Short answer. For a genuine retrenchment, yes. Article 283 sets the rate at one month's pay or half a month's pay for every year of service, whichever is higher. Check two things: that the one-month floor was applied, and that the ground really is retrenchment.
What the law says
In case of retrenchment to prevent losses and in cases of closures or cessation of operations of establishment or undertaking not due to serious business losses or financial reverses, the separation pay shall be equivalent to one (1) month pay or at least one-half (1/2) month pay for every year of service, whichever is higher.
Labor Code, Article 283 — Closure And Personnel Reduction. Read the full provision →
Half a month per year is the retrenchment rate
The article is explicit: In case of retrenchment to prevent losses ... the separation pay shall be equivalent to one (1) month pay or at least one-half (1/2) month pay for every year of service, whichever is higher. So the multiplier you were offered is the one the law prescribes for this ground, and an employer using it is not shortchanging you on the rate alone. The same lower rate applies to closures that are not due to serious business losses. It is the ground, not the employer's generosity, that fixes which figure applies.
The one-month floor and the fraction rule
Two arithmetic points are easy to lose. First, whichever is higher means half a month per year is compared against a flat one month's pay — so anyone with less than two years of service takes the flat month, and an offer of half a month for a single year is short. Second, a fraction of at least six months counts as one whole year, which can add half a month to the total. Ask for the computation sheet showing the rate, the years credited and the monthly figure used.
Whether the ground is really retrenchment
This is where the money usually is. Retrenchment under the article is retrenchment to prevent losses. If your position was in fact abolished as superfluous, that is redundancy, and redundancy carries the full month per year. Employers sometimes reach for the retrenchment label because it costs half as much. Look at what the notice actually says, at what management told the workforce, and at whether the business was being described as losing money at the time — and note whether your duties simply ended or were absorbed by someone else.
Before you sign the quitclaim
A release is normally presented together with the cheque, and signing it while the computation is unexplained is the step that is hardest to undo. There is no rule requiring you to sign on the spot. Ask for the breakdown in writing, compare it against your payslips and your actual start date, and confirm that unpaid wages, pro-rated thirteenth month pay and any unused leave convertible under your company's rules are being paid on top of separation pay rather than folded into it.