Can I pay after the patent expires?

If the patent fails to pay the annual fee within the time limit, it can be paid back within 6 months, and the late payment fee can be paid at the same time. If the overdue formalities are not completed within six months, the Patent Office will issue a notice of termination, giving the patentee two months, during which the patentee can apply for patent restoration. If the application is not filed within the time limit, the patent is invalid.