According to Paragraph 2 of Article 37 of the Marriage Law, the agreement or judgment on children's living and education costs does not prevent children from making reasonable demands to either parent when necessary that exceed the original amount of the agreement or judgment. Therefore, if the maintenance fees determined in the agreement or judgment are insufficient at the time of divorce, children can sue again to increase the maintenance fees, However, whether the maintenance fee can be changed depends on the necessity and possibility of change.
 Generally speaking, only when there is the necessity and possibility of change can the claim for change of alimony be supported by the court. In this regard, the Supreme People's Court's "Several Specific Opinions on the People's Court's Handling of Child Support in the Trial of Divorce Cases" clearly stipulates that children may file a lawsuit again to request an increase in maintenance fees under the following circumstances:
 (1) The original amount of alimony is not enough to maintain the actual local living standard
 (2) The actual needs have exceeded the original amount due to children's illness or school attendance
 (3) There are other justifiable reasons for the increase.
 Therefore, if we want to sue for changing maintenance fees, we need to submit corresponding evidence to the people's court:
 (1) Relevant evidence of increased expenses, such as the increase of living expenses, relevant evidence bills, and relevant payment bills for hospitalization, enrollment, and large expenses
 (2) Relevant certificates of income increase of the dependents, such as the taxpayer's salary and wage slip. Only through the above proof can we prove the necessity and possibility of changing maintenance fees, and the lawsuit request for changing maintenance fees can be supported by the people's court.
 Article 37 of the Marriage Law of the People's Republic of China
 After divorce, the other party shall bear part or all of the necessary living and education expenses for the children supported by one party. If the two parties fail to reach an agreement on the amount of the expenses to be borne and the length of the period, the people's court shall make a judgment.