USCIS decided against your application. The denial notice explains the reasons and states what options exist, which may include an appeal or a motion to reopen -- both with strict deadlines.
What happens next
Read the denial notice carefully and note any deadline. Talking to an accredited representative or immigration attorney is worth doing quickly.
Official USCIS wording
On September 9, 2025, we denied your Form N-400, Application for Naturalization, Receipt Number XXXXXXXXXXXXX. We sent you a denial notice that explains why we denied your case and your options. Please follow the instructions in the notice. If you do not receive your denial notice by September 24, 2025, please go to www.uscis.gov/e-request to request a copy of the notice. If you move, go to www.uscis.gov/addresschange to give us your new mailing address.