Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- When a full hijri year has passed and zakah becomes due, it must be paid.
2- It is not permissible to delay paying zakah after it has become due, unless one has a valid excuse.
3- It is permissible to pay zakah before it is due, by way of hastening it.
4- There may be some reasons why paying zakah at a time other than Ramadan is preferable to paying it during Ramadan
5- Giving charity to people is better in Ramadan than in any other month.
Answering your question, we would like to quote the following fatwa published on www.islamqa.info:
Firstly, when a full hijri year has passed and zakah becomes due, it must be paid, unless it is the zakah of agricultural crops, which must be paid on the day of harvesting, because Allah says:
“but pay the due thereof (their Zakah, according to Allah’s Orders, 1/10th or 1/20th) on the day of their harvest” (Al-An`am 6:141)
Zakah must be paid as soon as one full hijri year has passed, because Allah says:
“Race with one another in hastening towards forgiveness from your Lord (Allah), and Paradise the width whereof is as the width of the heaven and the earth” (Al-Hadid 57:21)
Ibn Battal said:
One should hasten to do good, for things change, death could come at any time, and delaying is not good.
Ibn Hajar said: Someone else added:
It is better in order to free oneself from blame and help others, more pleasing to the Lord and more likely to erase sin. (Fath al-Bari 3/299)
Secondly: it is not permissible to delay paying zakah after it has become due, unless one has a valid excuse.
Thirdly: it is permissible to pay zakah before it is due, by way of hastening it.
Hastening zakah means paying the zakah of two years or less, before it is due.
It was narrated from `Ali that the Prophet (peace and blessings be upon him) asked aAl-`Abbas to pay zakah two years in advance. (Abu `Ubayd al-Qasim ibn Sallam in al-Amwal, 1885. Al-Albani said in al-Irwa’, 3/346: it is hasan)
According to another report:
It was narrated from `Ali that Al-‘Abbas asked the Messenger of Allah (peace and blessings be upon him) about paying his zakah before it was due, and he allowed him to do that. (At-Tirmidhi, Abu Dawud, and Ibn Majah)
Fourthly: Giving charity to people is better in Ramadan than in any other month.
It was narrated that Ibn `Abbas said: The Messenger of Allah (peace and blessings be upon him) was the most generous of people, and he was at his most generous during Ramadan, when Jibreel met him. Jibreel used to meet with him every night and teach him the Qur’an. The Messenger of Allah (peace and blessings be upon him) was the most generous person, even more generous than the strong uncontrollable wind (in readiness and haste to do charitable deeds).” (Al-Bukhari and Muslim)
Al-Nawawi said: This hadith teaches us a number of things, including the fact that it is mustahabb to be generous during Ramadan.
So if a person’s zakah is due in Ramadan, or it is due after Ramadan but he pays it in advance during Ramadan in order to make the most of the virtue of paying it in Ramadan, there is nothing wrong with that. But if his zakah is due before Ramadan (for example, in Rajab), and he delays it so he can pay it in Ramadan, this is not permissible, because it is not permissible to delay zakah unless one has a valid excuse.
Fifthly: There may be some reasons why paying zakah at a time other than Ramadan is preferable to paying it during Ramadan, such as if there is a major disaster or famine in some Muslim country, then paying zakah at that time is preferable to paying it in Ramadan.
Another example is if many people pay their zakah during Ramadan to meet the needs of the poor, then the poor have no one to feed them at times other than Ramadan; in this case paying it at a time other than Ramadan is preferable, even if that leads to delaying zakah, out of consideration for the needs of the poor.
Sheikh Ibn ‘Uthyameen (may Allah have mercy on him) said:
It is permissible to delay zakah if that is in the interests of the poor and will not cause them harm. For example, in our country many people pay zakah in Ramadan and this gives the poor what they need or more than they need, but then during the winter, if that does not coincide with Ramadan, they will be in greater need and there are few people paying zakah.
In that case, it is permissible to delay zakah because that is in the interests of those who are entitled to it. (Al-Sharh al-Mumti` 6/189)
Almighty Allah knows best.