Short answer
Ordinary chewing gum breaks the fast, because its sugar, sweeteners and flavour dissolve and are swallowed. Tasting food with the tip of the tongue and spitting it out does not break the fast, but in the Hanafi school it is makruh unless there is a need, such as a cook checking the salt.
Chewing gum that releases sugar, flavour or other particles breaks the fast once these are swallowed, with qada only. Tasting food without swallowing is makruh tanzihi without need and allowed without dislike when there is a real need, such as cooking for others or checking food before buying it. Chewing food to soften it for a baby is allowed when there is no other way.
The four schools agree on this.
Explanation
Modern chewing gum is not a neutral object in the mouth. Even sugar-free gum contains sweeteners and flavourings that dissolve into the saliva and go down the throat, so chewing it breaks the fast. Nicotine gum also breaks the fast. The classical Hanafi texts called chewing plain resin makruh because it did not dissolve; that ruling does not apply to today's gum.
Tasting food. Touching food with the tip of the tongue to check salt or spice, then spitting it out, does not break the fast because nothing is swallowed. Doing it without a reason is makruh, since it brings the fast close to being broken. With a genuine need it is not disliked, for example:
- a cook preparing iftar for the family or a restaurant;
- a parent checking the temperature or taste of a baby's food;
- someone checking the quality of food before buying it.
Spit out what you tasted and wipe your mouth. If you swallow any of it, even by accident, the fast is broken and you make up one day. A taste that lingers after spitting does not break it.
The four schools agree on these rulings in substance: gum that dissolves breaks the fast, and tasting without swallowing is disliked without need. For other everyday cases, see the what breaks your fast checker.
The evidence
Quran, Surah Al-Baqara 2:187
أُحِلَّ لَكُمْ لَيْلَةَ ٱلصِّيَامِ ٱلرَّفَثُ إِلَىٰ نِسَآئِكُمْ ۚ هُنَّ لِبَاسٌۭ لَّكُمْ وَأَنتُمْ لِبَاسٌۭ لَّهُنَّ ۗ عَلِمَ ٱللَّهُ أَنَّكُمْ كُنتُمْ تَخْتَانُونَ أَنفُسَكُمْ فَتَابَ عَلَيْكُمْ وَعَفَا عَنكُمْ ۖ فَٱلْـَٰٔنَ بَٰشِرُوهُنَّ وَٱبْتَغُوا۟ مَا كَتَبَ ٱللَّهُ لَكُمْ ۚ وَكُلُوا۟ وَٱشْرَبُوا۟ حَتَّىٰ يَتَبَيَّنَ لَكُمُ ٱلْخَيْطُ ٱلْأَبْيَضُ مِنَ ٱلْخَيْطِ ٱلْأَسْوَدِ مِنَ ٱلْفَجْرِ ۖ ثُمَّ أَتِمُّوا۟ ٱلصِّيَامَ إِلَى ٱلَّيْلِ ۚ وَلَا تُبَٰشِرُوهُنَّ وَأَنتُمْ عَٰكِفُونَ فِى ٱلْمَسَٰجِدِ ۗ تِلْكَ حُدُودُ ٱللَّهِ فَلَا تَقْرَبُوهَا ۗ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ ءَايَٰتِهِۦ لِلنَّاسِ لَعَلَّهُمْ يَتَّقُونَ ﴿١٨٧﴾
It has been made permissible for you the night preceding fasting to go to your wives [for sexual relations]. They are clothing for you and you are clothing for them. Allah knows that you used to deceive yourselves, so He accepted your repentance and forgave you. So now, have relations with them and seek that which Allah has decreed for you. And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until the sunset. And do not have relations with them as long as you are staying for worship in the mosques. These are the limits [set by] Allah, so do not approach them. Thus does Allah make clear His ordinances to the people that they may become righteous.
The fast is holding back from eating and drinking until sunset, and dissolving gum is a form of eating.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Sawm, chapter on what is disliked for the fasting person. Tasting something or chewing it without need is makruh; the cook and the like are excused.
- al-Fatawa al-Hindiyya, Kitab al-Sawm, chapter on what is disliked and what is not. Chewing gum that breaks up and is swallowed breaks the fast.
- al-Mughni (Ibn Qudama), Kitab al-Siyam. Tasting food without need is disliked, and chewing gum whose parts are swallowed breaks the fast.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.