Both will do. According to the Interim Measures for Special Additional Deduction of Personal Income Tax, the starting time of the special additional deduction for children's education is the month when the children reach the age of 3, and the ending time is 1 month before entering primary school. This means that the child will be 3 years old in the deduction year. You can fill in the relevant information in advance before the child reaches 3 years old, and you can enjoy the special additional deduction for children's education in the month when the child reaches 3 years old.