In the Philippines, is it considered rude or impolite to call someone by their first name?

Dayang Marikit

Yes, but it depends on your rank, relationship and dynamics towards each other.

• It's not acceptable for children to address their parents and elders by their first names.
• Between siblings, elder siblings might take offense if younger siblings address them by their first names, they are rather addressed as (Kuya/Older Brother) and (Ate/Older Sister). The youngest sibling could be addressed as (Bunso) but it's perfectly acceptable to address them by their first names.
• In school and work settings, you would be required to address your teachers and work superiors as (Sir/Ginoo) and (Ma'am/Ginang). People would generally find it disrespectful to address your teachers and work superiors by their first names.