I forgot to pay the annual patent fee. What should I do when it expires?

Legal analysis: after applying for a patent, you need to pay the corresponding annual patent fee every year, and the annual patent fee is also increasing year by year. Usually, the annual patent fee is paid in advance one month before the expiration of the annual patent fee in the previous year. If the annual patent fee cannot be paid on time within the payment period, it can be paid within six months after the expiration of the annual patent fee, but a late fee will be incurred in the first month after the expiration of the patent fee, and the late fee will be increased every month. The patentee can recover the patent right by paying the patent fee and late payment fee. If the patentee fails to pay the relevant fees for more than six months, the patent shall be invalid.

Legal basis: Article 94 of the Detailed Rules for the Implementation of the Patent Law of People's Republic of China (PRC). The fees specified in the Patent Law and these Detailed Rules may be paid directly to the patent administration department in the State Council, or by other means specified by the post office, bank or the patent administration department in the State Council. If remittance is made by post office or bank, the correct application number or patent number and the name of the fee paid shall be indicated on the remittance slip sent to the patent administration department in the State Council. If it does not conform to the provisions of this paragraph, it shall be deemed that it has not gone through the payment formalities. If the fee is paid directly to the patent administrative department of the State Council, the payment date shall be the payment date; If payment is made by post office remittance, the postmark date of post office remittance shall be the payment date; If payment is made by bank remittance, the actual remittance date of the bank shall be the payment date. If the patent fee is overpaid, re-paid or wrongly paid, the party concerned may, within 3 years from the date of payment, request a refund from the patent administration department in the State Council, and the patent administration department in the State Council shall refund it.