What  is recommended for the Muslim on 
the day of 'Aashooraa.

What is obligatory upon the Muslim to do on the day of 'Aashooraa.. (tenth day of Muharram), and is Zakaat al-Fitr obligatory (on that day)? 

It is legislated for the Muslim to fast on the day of 'Aashooraa., for that which has been confirmed that the Prophet ordered fasting on (the day of) 'Aashooraa., however, when (the fasting of) Ramadhaan was obligated, whoever preferred to fast ('Aashooraa.) did so and whoever preferred not to (do so) did not. And there is no Zakaat al-Fitr (to be paid) on the day of 'Aashooraa. as there is on `Eed al-Fitr after the month of Ramadhaan.

The permissibility of fasting on the day of 'Aashooraa only

Is it permissible to fast 'Aashooraa. just one day?

It is permissible to fast the day of 'Aashooraa. (tenth day of Muharram) just one day, however, it is better to fast the day before it or the day after it (also) and this is the established Sunnah of the Prophet who said: (If I am (still) here next year, then certainly I shall fast the ninth (day of Muharram), [(reported by) Muslim, Ahmad, Ibn Maajah, Ibn Abee Shaybah, at-Tahaawee, al-Bayhaqee and al-Baghawee]. Ibn 'Abbaass said: (along with the tenth (day of Muharram).

Fasting voluntary fasts whilst having days (outstanding) from Ramadhaan

What is the ruling regarding the one who has days of fasting remaining from the month of Ramadhaan yet wishes to fast voluntary fasts or fast the day of 'Aashooraa. (tenth day of Muharram)? For example, he wants to fast both the tenth and eleventh days with the intention of making up (the missed fasts of Ramadhaan) and not the fast of the day of 'Aashooraa. Also, is it permissible for one to fast the day of 'Aashooraa., even if he has fasts to make up from the month of Ramadhaan? And is it permissible for one who has days to make up from Ramadhaan to fast the Day of 'Aashooraa. and the day before it or the day after it, with the intention of making up (what he has missed)?

He should not do the voluntary fast whilst he has a day or days to make up from Ramadhaan. Rather, he should begin by making up that which he has (outstanding) from Ramadhaan, then do the voluntary fast. Secondly, if he fasted the tenth and eleventh days of the month of Muharram with the intention of making up that which he has (outstanding) from the days he did not fast in the month of Ramadhaan, then that is permissible and sufficient in making up two days from that which he has outstanding; For that which the Prophet said: (The reward of deeds depends upon the intentions and every person will get the reward according to what he has intended,...).

And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad and his family and his companions.