Answer: The traffic accident determination letter should be signed by the parties involved, but there is no legal requirement for both parties to sign. If the party concerned refuses to sign, the traffic police shall indicate the situation on the traffic accident determination form. The traffic accident determination letter shall be signed or stamped by the traffic police and stamped with the special seal of the traffic management department of the public security organ, and the parties shall be notified to apply for review, etc. Legal Basis "Regulations on Procedures for Handling Road Traffic Accidents" The 24th Road Traffic Accident Determination Letter shall be signed by the parties involved and served on site. If the party concerned refuses to sign or accept it, the traffic police shall indicate the situation on the road traffic accident determination form. Article 64 The road traffic accident determination letter shall be signed or stamped by the traffic police, and shall be affixed with the special seal of the traffic management department of the public security organ for handling road traffic accidents. Article 65: The road traffic accident determination letter shall be delivered to the parties respectively within three days after it is produced, and the rights and time limits for applying for review, mediation and filing of civil lawsuits shall be notified.