It is Permissible to delay making up missed Ramadan Fasts until before the next Ramadan comes, and this is for those who broke the fast for a reason such as sickness, travel, menstruation and the like

Abu Salama reported: I heard 'A'isha (Allah be pleased with her) as saying: I had to complete some of the fasts of Ramadan, but I could not do it but during the month of Sha'ban due to my duties to the Messenger of Allah ﷺ or with the Messenger of Allah ﷺ.

حَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ اللَّهِ بْنِ يُونُسَ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ أَبِي، سَلَمَةَ قَالَ سَمِعْتُ عَائِشَةَ، - رضى الله عنها - تَقُولُ كَانَ يَكُونُ عَلَىَّ الصَّوْمُ مِنْ رَمَضَانَ فَمَا أَسْتَطِيعُ أَنْ أَقْضِيَهُ إِلاَّ فِي شَعْبَانَ الشُّغُلُ مِنْ رَسُولِ اللَّهِ ﷺ أَوْ بِرَسُولِ اللَّهِ ﷺ .

This hadith is narrated on the authority of Yahya b. Sa'id with the same chain of transmitters but with this variation that he said that ('A'isha did not observe fast but in Sha'ban) out of regard for the Messenger of Allah ﷺ. (In another version, the words are):" Yahya said: I think it was due to the regard for the Apostle of Allah ﷺ."

وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا بِشْرُ بْنُ عُمَرَ الزَّهْرَانِيُّ، حَدَّثَنِي سُلَيْمَانُ، بْنُ بِلاَلٍ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، بِهَذَا الإِسْنَادِ غَيْرَ أَنَّهُ قَالَ وَذَلِكَ لِمَكَانِ رَسُولِ اللَّهِ ﷺ .

This hadith is reported on the authority of Yahya with the same chain of transmitters but no mention is made of the duty to the Messenger of Allah ﷺ.

وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا عَبْدُ الْوَهَّابِ، ح وَحَدَّثَنَا عَمْرٌو النَّاقِدُ، حَدَّثَنَا سُفْيَانُ، كِلاَهُمَا عَنْ يَحْيَى، بِهَذَا الإِسْنَادِ وَلَمْ يَذْكُرَا فِي الْحَدِيثِ الشُّغْلُ بِرَسُولِ اللَّهِ ﷺ .