Switching to casual speech

Why

Dropping polite speech is a sign of closeness, so it's agreed on, not assumed.

Do

• Let the older person suggest it.
• Agree clearly when it's offered: 네, 편하게 할게요.

Avoid

• Don't switch on your own with someone older.
• Don't switch back to formal speech when you're upset — it reads as cold.

Useful sentence

우리 말 편하게 할까요?uri mal pyeonhage halkkayo?Shall we speak casually with each other?

These are general customs; people, generations and situations vary — kindness covers most mistakes.