The two parties shall first reach an agreement on the additional alimony. If they fail to reach an agreement, they may file a lawsuit with the people's court to request an increase in alimony. According to the provisions of China's Civil Code, the number of expenses to be borne and the length of the time limit shall be agreed by both parties; If the agreement fails, the people's court shall make a judgment. The agreement or judgment mentioned in the preceding paragraph shall not prevent children from making reasonable demands to either of their parents when necessary in excess of the amount originally set in the agreement or judgment.
 Legal basis:
 Article 58 of the Interpretation of the Supreme People's Court on the Application of the Marriage and Family Part of the Civil Code of the People's Republic of China (I) shall be upheld by the people's court in any of the following circumstances, if a child demands that his or her affordable father or mother increase maintenance fees:
 （1） The original amount of alimony is not enough to maintain the actual local living standard;
 （2） The actual needs of the children have exceeded the original amount due to illness or school attendance;
 （3） There are other justifiable reasons to increase.