All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, the Imaams of the four Schools of jurisprudence and the majority of the former and contemporary scholars agreed that the women who broke the fast for a valid reason, like menses and pregnancy are not obliged to make it up immediately after the month of Ramadan and that they have time until the next Ramadan comes. However, it is not permissible for them to delay it until the month of Sha'baan of the next year is over.
Therefore, a woman who has to make up some missed days of Ramadan and her husband is present with her and he has a need for sexual intercourse with her, then she should not hasten to make up for the missed days except with his permission since there is plenty of time to do so. However, if there is not much time left to make up the fasting, then a wife is not obliged to seek the permission of her husband in order to fast, and he has no right to prevent her from fasting the days she is obliged to make up since there is not much time left for doing so. When the scholars interpreted the Hadeeth "It is not permissible for a woman to fast when her husband is present except with his permission.", they interpreted the expression "except with his permission" to mean optional fasting other than the missed days of Ramadan; the same thing applies to the obligatory fasting when there is not much time left to make it up [i.e. that she does not need to seek his permission].
Therefore, you are not obliged to seek your husband's permission in order to make up for the obligatory missed days of fasting when there is not too much time left [for the starting of the next Ramadan], and your husband has no right to prevent you. Similarly, if he gives you permission to fast and then he changes his mind and wants you to break the fast after you already started fasting, then you are not obliged to obey him, as he has no right to prevent you then.
For more benefit, please refer to Fatwa 85464.
Allaah Knows best.