How to calculate the annual fee for invention patents?

The annual fee for invention patent is calculated in 1 ~ 3 years (year) 900 years (year) 1200 years (year) 7 ~ 9 years (year) 2000 years (year) 10 ~ 13 ~ 65400 years. The patent applicant or patentee may request the reduction or exemption of the following patent fees: (1) application fee (excluding publication and printing fee and application surcharge); (2) the substantive examination fee for an application for a patent for invention; (3) Annual fee (annual fee within six years from the year when the patent right is granted); (4) review fee. If the patent applicant or patentee meets one of the following conditions, he may request China National Intellectual Property Administration to reduce or exempt the above fees: (1) an individual with an average monthly income of less than 3,500 yuan (42,000 yuan a year); (2) Enterprises with taxable income of less than 300,000 yuan in the previous year; (3) Institutions, social organizations and non-profit scientific research institutions. Where two or more individuals or units are the same patent applicant or patentee, they shall abide by the provisions of the preceding paragraph respectively.