tú or usted?

The rule

tú is for friends, family, children, and colleagues roughly your own age once you are on first-name terms (in Spain that usually happens on day one). usted is for a stranger older than you, an official, a customer, or anyone you want to keep at a polite distance. Spanish moves to tú much faster than French moves off vous, but with an adult you do not know, start with usted: the move down to tú is theirs to offer, not yours.