The reason can be written as being abroad for a long time, unable to pay, or being hospitalized for a long time.
In general, you only need to submit a patent recovery request and pay the patent recovery request fee and related annual fees. Generally, the patent office will not carefully check whether the reasons written are sufficient.
After the patent application is granted the patent right, the patentee shall pay the annual fee for the next year in advance one month before the expiration of each year. If the annual fee is not paid or not paid in full, the Patent Office will issue a notice of payment, informing the patentee to pay it within 6 months from the date when the annual fee should be paid, and at the same time pay the late fee. The amount of the late payment fee is calculated by adding 5% of the full annual fee of the current year for every 1 month that exceeds the prescribed payment time; If it is not paid at the expiration of the period, the patent right shall be terminated from the date when the annual fee payable expires.