1. According to the regulations of the National Natural Science Foundation of China, only after the project is completed or expired can the final evaluation and summary of the project be made and the final acceptance be given. So, if the project is still in progress, you won't receive the evaluation every year.
2. For important or special projects, the National Natural Science Foundation of China will strengthen supervision and evaluation, such as organizing experts to conduct on-the-spot investigations and holding project reporting meetings, rather than just evaluating by letters.
3. The National Natural Science Foundation of China will also adjust the frequency and form of evaluation according to the actual situation and work needs, and sometimes it will not send a letter of evaluation every year.