The condition of yearly term maturity applies to the commodities on which the Lawgiver said Zakat is due, and this includes silver, gold, modern paper currency and livestock. Paper currency is analogous to silver, therefore, it takes the case of silver. There is no Zakat on salary, earned income from wage earners or professionals or independent contractors until such money matures in a full year. There is no such thing as paying your Zakat on the day you receive your pay check. What the wage earner must know is that he or she can purify that money with charity (sadaqah) anytime they cash the pay check. Allah (SWT) states: "And in their wealth and possessions (was remembered) the right of the needy, he who asks and he who (for some reason) was prevented (from asking)." (Al-Qur'an, 51: 19).
We can deduce from the concept of "yearly maturity" of wealth on which Zakat is due as encouraging, among other things, saving on the part of the Zakat payer, and enhances the chances for eradicating poverty, because if the poor receives his rightful share of Zakat there will be the possibility that he can take Zakat money and invest it and become a Zakat payer instead of recipient. This possibility will be lost if he receives few Zakat dollars every month. To say that the wage earner just brings his check home and spends everything on necessities and lives from check to check with nothing left over means the person is eligible for Zakat.
Using farm produce as analogous to salary for Zakat is wrong analogy. As Imam Al-`Abadi said, these are two different categories of money. $2, 500.00 cash can be invested by the person and expect a good return whereas it will be difficult to invest a bushel of corn. It can be traded as a commodity, which is what it is. This why we must know that analogy has rules that must be followed before it is applied. Certainly the jurists are unanimous that earned income, known as almal al-mustafadah, should either be added to existing money and wait until that amount reaches maturity and then give their Zakat; or if there is no money on hand the time one possesses this money, he or she should wait one full year before assessing it for Zakat.
Zakat is one of the five pillars of Islam and a vital element in the religion of Islam. It is the twin sister of Salaat. In Al-Qur'an, Allah (SWT) stated: "So establish regular Prayer and give regular Alms; and obey the Messenger; that you may receive mercy." (Al-Qur'an, 24: 56) Also, "...Establish regular Prayer and give regular Alms, and loan to Allah a beautiful loan...." (Al-Qur`an, 73: 20) "And they have been commanded no more than this: to worship Allah, offering Him sincere devotion, being true (in faith); to establish regular Prayer and to practice regular charity; and that is the religion right and straight." (Al-Qur`an, 98: 5)
In a famous Hadith reported by `Umar Bin Khattab (raa), the Messenger of Allah (S.A.W) responded to Jibreel (A.S) and said: "... Islam is to testify that there is no deity but Allah and Muhammad is the Messenger of Allah, to perform the prayer, to pay Zakat, to observe fasting in Ramadan, and to make pilgrimage to the house of Allah if you are able to do os...." (Bukhari, Muslim)
There is consensus among Muslim scholars that it is mandatory on every believer who is financially able. Whoever knowingly denies this obligation, while he possesses the minimum amount, would be considered a disbeliever and a renegade from Islam. Whoever is stingy, or tries to cheat, is considered among the wrongdoers. Zakat is mandatory on four categories of items.