What is the correct overtime rate, and can my company make me waive it?

Why

The normal hours of work are eight a day under Article 83. Article 87 then fixes what happens past that: work beyond eight hours is paid additional compensation equivalent to the regular wage plus at least 25% of it, and work performed on a rest day or holiday that extends beyond eight hours is paid an additional 30% of the hourly rate applicable on that day.

The compounding is what trips people up, because the 30% is taken on the day's rate and not on the ordinary rate. Starting from your hourly rate, overtime on an ordinary day is 125%. On a rest day or special non-working day, where the day's rate is already 130%, overtime is 130% of that, or 169%. On a regular holiday, where the day's rate is 200%, overtime is 260%. On a regular holiday that is also your rest day, the day's rate is 260% and overtime is 338%.

Article 88 is short and absolute: undertime work on any particular day shall not be offset by overtime work on any other day, and permission given to an employee to go on leave on some other day of the week shall not exempt the employer from paying the additional compensation. The reason is arithmetic. Undertime is deducted at 100% while overtime is paid at 125%, so an offset quietly takes money from the employee.

Overtime is generally voluntary, but not always. Article 89 lists when an employer may compel it: when the country is at war or under a national or local emergency declared by Congress or the President; when necessary to prevent loss of life or property, or in case of imminent danger to public safety from an actual or impending emergency such as a serious accident, fire, flood, typhoon, earthquake or epidemic; when urgent work is needed on machines, installations or equipment to avoid serious loss; when necessary to prevent loss or damage to perishable goods; and where completing work started before the eighth hour is necessary to prevent serious obstruction to the business.

A waiver does not hold. The right to overtime pay is a statutory benefit and cannot be bargained away, so an agreement to render overtime without additional pay is contrary to law and void. What an employer may lawfully do is adopt a compressed workweek under DOLE guidelines, which is a different arrangement with its own conditions and requires genuine employee consent.

The exclusions in Article 82 matter here as much as the rates. Managerial employees, field personnel whose actual hours cannot be determined with reasonable certainty, members of the employer's family dependent on them for support, domestic workers, persons in the personal service of another, and workers paid by results are outside these provisions. Job titles do not settle it, because whether someone is genuinely managerial turns on the powers they actually exercise rather than the word printed on their ID.