有空联系。

You usually say this at the very end of a conversation. It works perfectly as you are walking away. You can also send it as a final text message. It often follows a 'goodbye' or 'see you later.' You don't need to wait for an answer. It is a statement of intent, not a question. Just drop it and wave goodbye.

Use it with friends you don't see every day. It is great for former colleagues you actually liked. Use it after a pleasant first meeting with a neighbor. It works well when ending a phone call with family. If you had a nice chat at a party, say it. It keeps the door open for future hangouts. It makes you look polite and socially savvy.

Don't use it if you are actually setting a firm date. If you say 'See you Tuesday,' don't add this. It might make the Tuesday plan feel optional. Avoid it with your boss during a serious performance review. It might sound too casual or dismissive. Don't use it if you never want to see them again. In that case, just stick to a standard 再见.

Chinese culture values 'mianzi' or face. Directly saying 'I don't have time for you' is rude. This phrase provides a polite buffer for everyone. It is part of the 'polite guest' culture. Sometimes people say it just to be nice. It doesn't always mean they will call tomorrow. It is about maintaining a harmonious atmosphere. It’s the social glue of modern Chinese cities.

You might hear 有空聚聚 (Let's gather when free). Or 常联系 (Contact often), which is slightly more enthusiastic. If you are texting, you might see 有空聊 (Chat when free). They all share that same friendly, flexible vibe. Choose the one that fits your energy level. Just remember: the 'free time' part is the key!