誠に申し訳ございませんでした。 — I am truly and deeply sorry. (Cultural · Communication, Formal to Client, JLPT N3)

Gesture & etiquette

A deep bow of 30-45 degrees is expected — the more serious the error, the deeper the bow. In business contexts, this is often done standing. Maintain the bow until the other party verbally acknowledges the apology.

「申し訳ございません」is the most formal apology in Japanese — used when a serious mistake has been made or someone has been significantly inconvenienced. 「誠に」(truly/sincerely) amplifies the sincerity. Unlike English apologies, repeating and elaborating on the apology is expected — a single 'sorry' can feel insufficient.