One person's numbers
Kim is a staff nurse at a private hospital in Iloilo City with a basic salary of ₱25,000. She works mostly nights, so every payslip has a night shift differential line (at least 10% of her hourly rate for hours between 10 p.m. and 6 a.m.), and she was rostered on Holy Week, Christmas Eve and New Year's Eve.
Over 2026, her night differential adds roughly ₱2,300 a month and holiday premiums another ₱6,000 for the year — about ₱333,600 in total pay. Her 13th month is still ₱25,000: ₱300,000 of basic salary ÷ 12. She'd hoped for about ₱28,000; the difference is all excluded pay.
Shift workers: why the 13th month feels smaller
For shift workers — nurses, BPO agents, security guards, factory crews — the gap between gross pay and basic pay can be 10–20%. The 13th month law was written around basic salary, and DOLE advisories list night differential, overtime, premium and holiday pay as exclusions. The only exception: if your employment contract, a CBA or a long-standing company practice includes them, your employer must keep doing so.
If you're comparing job offers, a higher basic salary is worth more than an equivalent allowance: it raises your 13th month, your overtime rate and, for SSS, your monthly salary credit.