After entering China, accommodation registration is a legal duty. In hotels, the front desk registers you automatically through the police system — you do nothing (just keep the check-in slip). But if you stay in private accommodation (a friend's home, homestay, short-term rental), you or the host must register a Temporary Accommodation Registration Slip at the local police station within 24 hours of checking in.
When does the 24 hours start? From the moment you actually move in. Arrive at a friend's at 3pm, register by 3pm the next day. Weekends do not extend the deadline — go the same day or call ahead about duty arrangements.
Missing the deadline: usually a warning and a fine (often a few hundred yuan); serious cases can affect future visas and entry. Repeat or severe violations may shorten your stay or bar re-entry.
Common myths: Airbnb/homestay ≠ exempt (hosts usually help, but the duty is yours); every change of address needs a new registration, even within one city; keep the slip — you will need it for visa extensions and residence permits. Bottom line: private stay = police station the same day.