I have a habit of fasting Nafl (voluntary) fasts. I have a few questions:
1. Once I was keeping fast on Thursday. While sleeping alongside my wife, I indulged in foreplay with her and ejaculated. In this case what is the kaffārah?
2. Once I was keeping fasts for nine days of Zhul Hijjah. On the fifth fast, the same thing happened as mentioned above. What is the kaffārah for this. Then I continued fasting. Is the reward valid for the nine days or did I lose the reward due to breaking one fast (I stayed the whole day as if I was fasting)
3. In the above cases I acted as if I was fasting. So during Ghusl, do I have to take water for gurgling and in my nose deep inside, as we do for a normal Ghusl or do I take Ghusl like a fasting person without taking the water deep inside my mouth and nose?
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
1. In principle, having relationship with one’s wife leading to ejaculation renders the fast invalid. Hence one Qadhā (make up) fast is due on you.  However there is no kaffārah due. In any case, seek Allāh Taālā’s pardon as it is not permissible to break a voluntary fast without an excuse. 
2. The ruling is the same for the fast broken on the 5th fast of Zhul Hijjah. One Qadhā is
due on you at a later time. Furthermore, if one’s fast is invalidated in a voluntary fast, there is no reason to continue fasting for the remainder of the day.
An individual will be rewarded for each fast in the first nine days of Zhul Hijjah. Based on the sincerety of your intention, it is hoped from Allāh that you will be rewarded for the fifth fast also.
3. You have stated that despite the invalidation of your fast, you continued to fast the remainder of the day. However this was not necessary. Therefore, after the invalidation of the fast, it is perfectly fine to gargle whilst making Ghusl.
And Allah Ta’āla Knows Best
Mawlana Abdul Azeem bin Abdur Rahman,
Student Darul Iftaa
Checked and Approved by,
Mufti Husain Kadodia.
 (وإن أنزل بقبلة أو لمس فعليه القضاء) لوجود المنافي معنى - وهو الإنزال بالمباشرة (اللباب في شرح الكتاب, ج 2, ص 381:دار السراج)
 (ومن دخل في صوم التطوع أو في صلاة التطوع ثم أفسده قضاهما) وجوباً، لأن المؤدى قربة وعمل فنجب صيانته بالمضي عن الإبطال؛ وإذا وجب المضى وجب القضاء بتركه؛ ثم عندنا لا يباح الإفطار فيه بغير عذر في إحدى الروايتين، لما بيناه، ويباح بعذر، والضيافة عذر، لقوله صلى الله عليه وسلم: (أفطر يوماً مكانه) (1) . هداية.
وفي رواية عن أبي يوسف: يجوز بلا عذر وهي رواية المنتقى، قال الكمال: واعتقادي أن رواية المنتقى أوجه (اللباب في شرح الكتاب, ج 2, ص 391-392:دار السراج)