1. The patentee fails to pay the annual fee within the prescribed time limit, resulting in overdue payment order.
2. Although the patentee has paid the annual fee, due to various reasons, the Patent Office failed to record the annual fee in time, which led to the overdue payment instruction.
3. The patentee fails to pay the overdue fine within the prescribed time limit, which leads to the ruling of overdue fine.
4. The patentee fails to submit the patent fee reduction request within the prescribed time limit, which leads to the overdue payment order.
5. The patentee's bank account information is incorrect, resulting in the Patent Office being unable to receive the annual fee, which leads to the overdue payment bill.
6. Other reasons, such as system failure and network failure.
If your patent payment slip shows overdue, I suggest you contact the patent office or patent agency as soon as possible to find out the specific situation and seek a solution.