I.
It is permissible for the one who owns the minimum threshold of wealth (nisab) to hasten to pay zakah before one year has passed. It was soundly narrated that the Prophet (blessings and peace of Allah be upon him) granted a concession to al-`Abbas allowing him to pay his zakah before one year had passed. Narrated by Abu Dawud, 1626.
Ibn Qudamah (may Allah have mercy on him) said:
Whenever zakah becomes obligatory, which is when wealth reaches the minimum threshold, it is permissible to give zakah in advance.
This is the view of al-Hasan, Sa`id ibn Jubayr, az-Zuhri, al-Awza`i, Abu Hanifah, ash-Shafa`i, Is-haq and Abu `Ubayd… because of the report of `Ali, according to which al-`Abbas asked the Messenger of Allah (blessings and peace of Allah be upon him) about hastening to give obligatory charity before it becomes due, and he granted him a concession allowing him to do that.
According to another version, he asked about hastening to give zakah and he granted him a concession allowing him to do that. Narrated by Abu Dawud.
End quote from Al-Mughni, 4/79.
The hadith about al-`Abbas (may Allah be pleased with him) hastening to give obligatory charity was classed as authentic (hasan) by al-Albani in Irwa’ al-Ghalil, 857.
II.
When giving zakah, it is stipulated that the giver should intend that it is the zakah of his wealth when giving it, because the Prophet (blessings and peace of Allah be upon him) said: “Actions are but by intentions, and each man will have but that which he intended.” Narrated by al-Bukhari (1) and Muslim (3530).
Based on that, no one has the right to give zakah on behalf of anyone else except with his knowledge, and the owner of the wealth should have delegated that person to give zakah on his behalf.
So long as your wife is aware that you are giving zakah on her behalf, there is nothing wrong with that.
Shaykh `Abd al-`Aziz ibn Baz (may Allah have mercy on him) was asked:
Is it permissible for my husband to give the zakah on my wealth on my behalf, noting that he is the one who gave me the wealth?
He replied:
It is obligatory for you to give the zakah on your wealth, if you possess the minimum threshold of wealth or more in the form of gold or silver or other kinds of wealth that are subject to zakah. If your husband gives it on your behalf with your permission, there is nothing wrong with that. Similarly, if your father or your brother or someone else gives it on your behalf with your permission, there is nothing wrong with that.
End quote from Majmu` Fatawa ash-Shaykh Ibn Baz, 14/241.
And you will have a reward for that, if Allah wills, and that is also an act of kindness to your wife. It is included in the words of the Prophet (blessings and peace of Allah be upon him): “You will never spend on maintenance, seeking thereby the Countenance of Allah, but you will be rewarded for it, even a morsel that you put in your wife’s mouth.” Narrated by al-Bukhari (1295) and Muslim (1628).
III.
If you realise that you have given more zakah then you are obliged to, then this extra amount comes under the heading of voluntary charity, and you cannot intend it to be the zakah of your wife or to be the zakah of your wealth for future years, as has been explained previously in the answer to question no. 141595.
And Allah knows best.
