# Courtesy accidental

Source: https://arcosounds.com/glossary/courtesy-accidental
Also known as: cautionary accidental, reminder accidental

**A courtesy accidental is a sharp, flat, or natural printed to confirm a pitch the reader might otherwise doubt, often in parentheses, and it changes nothing about how the note is played.**

Accidentals last to the end of the measure, so the first note of the following bar reverts to the key signature. A good editor prints a courtesy natural on that note anyway, because a player mid-phrase should not have to reason about barline rules at speed.

They also appear after a key change, after a passage that used many accidentals, and on the same pitch in a different octave, all situations where an experienced reader hesitates. Parentheses mark them as reminders rather than new instructions.

For a student, the useful lesson is the inverse: where a courtesy accidental is absent, the rule still applies. The barline cancels; the key signature returns.

Canonical source: https://arcosounds.com/glossary/courtesy-accidental