How do you cite an AI answer?
Carefully, and less often than the conversation made it feel like you should. The rules are still settling, but the principles underneath them are already stable.
Cite an AI answer the way you cite a tool: name the tool and version, give the date, and treat what it said as something you were told rather than something you looked up. What you actually cite should be the recoverable sources you verified yourself. Style guides carry rules for this and they differ, so the durable habit is to disclose the tool's role and credit the real sources.
A conversation with a tool, not a source.
An answer from a model is not recoverable the way a paper is. Your reader cannot look it up; it was generated for you, in response to your wording, by a version that may already be superseded. That is why the major style guides treat it like software or personal correspondence: credit it in the text with the tool, the model version and the date, and keep it out of the reference list, where sources live only if a reader could find them. The details differ between guides and are still being revised, so check the current rules of whichever one your work follows.
Cite the source, not the summary.
The deeper rule is about what deserves the citation at all. An AI answer is a summary of things it read, generated with no index to consult, and the summary is yours to verify, not to transmit. When an answer points at a paper or a passage, find that document, read the part it is talking about, and then cite the document. What you publish then rests on recoverable sources with real provenance, and the AI's contribution stays where guides want it: a disclosed tool that helped you get there.
Say what you asked.
Disclosure completes the practice. Because an answer depends on the prompt, a serious use of AI in writing describes what was asked and how the output was used, often in a methods note or appendix. The habit scales down painlessly: a sentence in your notes naming the tool, the question and the date captures the same record. It also pairs naturally with grounded tools, where answers arrive with citations you can check before anything gets cited onward. The point of all three habits is the same: a reader of your work can retrace every step you took.