Allah (swt) says in the Quran - "Who establish prayer and give zakah, and they, of the Hereafter, are certain [in faith]."
الَّذِيۡنَ يُقِيۡمُوۡنَ الصَّلٰوةَ وَيُؤۡتُوۡنَ الزَّكٰوةَ وَهُمۡ بِالۡاٰخِرَةِ هُمۡ يُوۡقِنُوۡنَؕ
Zakah is obligatory if five conditions are met:
1) Islam
2) freedom from slavery
3) ownership of the "Nisaab" (amount upon which Zakah becomes due)
4) completion and stable ownership
5) completion of a year, except in the case of produce.
The categories of wealth upon which Zakah is obligatory are four:
freely grazing livestock
produces
moveable valuables (i.e. gold, silver, and paper money etc)
trade items
People who deserve Zakah:
1) For the poor and utterly destitute
2) For the poor who are needy
3) For the officials who collect and distribute it
4) For those who need additional attraction to Islam, whether Muslims or non-Muslims
5) For the liberation of slaves and captives
6) For helping people who are burdened with legal debt
7) For those who are struggling in the way of Allah in Jihad
8) For the travelers who are cut off from their homeland. They are to be given according to their need except for the officials who work to collect and distribute the Zakah, since they are given according to a fair and agreed upon salary, even if they are rich.
It fulfills the obligation to hand over the Zakah to the Khawarij (a group of Muslims who dissented from the companions of the Prophet (saw) and Bughaat (those who rebelled against a righteous Imam)) and the likes if they take control and rule the land.
It fulfills the obligation if the ruler takes the Zakah by force or by one's consent, and whether he is a just or an unjust ruler.
It does not fulfill the obligation to give the Zakah to a non-believer (other than those who need additional attraction to Islam), a slave, rich person, one's dependents, or a member of Bani Hashim (descendents of the Prophet (saw)).
If after giving the Zakah to an undeserving person out of ignorance the person comes to know about it, his obligation is not fulfilled except for the case that he gave to someone thinking that the person was poor and later on found out that he was rich.
The Zakah of freely grazing livestock is of three kinds: camels, cattle, goats and sheep.
The Zakah on them becomes obligatory on two conditions:
1) The animals are e grazing for a year or more
2) They are kept for milk and reproduction and not for work.
If they are for sale or trading, they are then considered trade items.
The Zakah of Camels:
4 camels or less: there is no Zakah on them.
24 camels and less: for each 5, one sheep is due.
25-35 camels: a one-year old she-camel, if not available, a two-year old he-camel.
36-45 camels: a two-year old she-camel.
46-60 camels: a three-year old she-camel.
61-75 camels: a four-year old she-camel.
76-90 camels: two, two-year old she-camels.
91-120 camels: two, three-year old she-camels.
More than 120 camels: for every 40, a two-year old she-camel is due; and for every 50, a three-year old she-camel is due.
Zakah of Cows:
Less than 30 cows: there is no Zakah on them.
30-39 cows: one, one-year old calf.
40-59 cows: one, two-year old calf.
60 cows or More: for every 30 a one-year old calf; and for every 40 a two-year old calf.
Zakah of Sheep and Goats:
Less than 40 sheep: there is no Zakah on them.
40-120 sheep: one sheep.
121-200 sheep: two sheep.
201-399 sheep: three sheep.
400 sheep or More: for every 100, one sheep is due. Zakah on Land Produce: It is obligatory upon three conditions:
1) The produce Could be measured by amount and stored, like barley and wheat of grains and like raisins and dates of fruits. But that which is not measured by amount and stored, like fresh vegetables and legumes, have no Zakah
2) It reaches the minimum amount (Nisaab), which is 653 kilograms
3) The person who will pay the Zakah has the Produce in his possession at the time when it is obligatory to pay Zakah, i.e., when the signs of ripeness show on the fruit and crops and they are ready for harvest.
The Zakah on Agricultural Products:
Products that are produced without efforts of irrigation, thus being the product of rainwater or free flowing streams and springs, have a Zakah rate of 10% (1/10)
The Zakah on agricultural product produced by effort and labor in irrigation is 5% (1 / 20th)
That which is partially by effort and partially without, is according to the greater of the two; the counting would be according to the number of the days that effort and labor is used
The Zakah on Moveable Valuables:
1) Gold: Zakah is due on gold only when it reaches 85 grams
2) Silver: Zakah is due on silver only when it reaches 595 grams
Zakah is due on money in any of its forms and currencies (e.g., bank notes) when its value is equivalent to the amount of the gold or silver mentioned above.
Since the prices of gold and silver vary from time to time and from country to country, Zakah should be based on whichever of the two works out better for the poor. The Zakah on moveable valuables and money is one fortieth, 1/40 (2.5%).
Jewelry and ornaments that are for daily use have no Zakah on them. However what is used for trade and savings must have the Zakah paid on them. It is allowed for women to wear what is customary of gold and silver jewelry. It is allowed to put a small amount of silver on utensils, and it is also allowed for men to have a small amount of silver in the likes of a ring and glasses.
Gold is prohibited to have on utensils and it is prohibited for men except a minute amount in something that is used for some other purpose, like a button or a gold tooth, without them resembling women.
If a person has wealth that fluctuates, increasing sometimes and decreasing at others, then he should specify a day when he takes inventory and calculates his wealth and pays the 1/40 (2.5%) on that, even if a year has not passed.
Those who are salaried or who have fixed incomes from rental real estate properties, for instance, have no Zakah due on them unless they save some of that amount. They must pay the Zakah of the saved amount if a complete year passes while the saved amount is in their possession. If it is difficult to calculate, they simply choose a day to reckon their account as mentioned above.
Zakah on Debts: If a person loans some money to a rich person, or if the debtor has sufficient funds and it is possible to get the money back from him, the Zakah for that loan is to be calculated and paid when the money is recovered for each of the years that lapsed, even if they are many. But if the debt is with someone who is bankrupt, there is no Zakah due since the person is not certain about its recovery and has no control over it.
There is no Zakah for trade items except with four conditions:
1) That the payer of the Zakah owns them
2) That he intends to trade with them
3) That they reach the minimal amount, which is like that of gold and silver (whichever is lesser)
4) That a year has lapsed while these items are in his possession
If these four conditions are fulfilled, he must pay the Zakah due from the value of the inventory. If the items do not reach the minimal amount of Zakah and the person is in possession of gold, silver or other money, he adds them to the value of the trade items to reach the minimal amount. If one intends to use the trade items for private use, like clothes, house and car, there is no Zakah due on them. If he changes his intention (you decide to use the items for trade again), he calculates the year from the time he changes his intention. possession.
Conditions of Zakat-ul-Fitr:
Zakat-ul-Fitr is two and a quarter kilos of staple food of the country in which it is being given. This amount is per person, male or female, and his dependents.
It is beloved to give it out on the Eid Day before the prayer of the Eid. It is not allowed to delay it past the prayer of the Eid but one may give it out a day or two before Eid. One may also give to one person an amount of food that is enough for a group and vice versa.
It is obligatory to distribute the Zakah immediately as it becomes due and the guardian is responsible to give Zakah on behalf of children and the insane.
It is Sunnah for the responsible person to distribute it personally and let it be known to the people. Intention for the person on whose behalf the Zakah is given is necessary.
It is important to note that voluntary charity would not suffice for obligatory Zakah, even if the person gave all his wealth away.
It is preferable to give the amount of Zakah to the poor of the country where the person live but in case of some overwhelming need, sending it to other countries is also allowed. Giving Zakah two years in advance is proper and allowed, if the wealth reaches the amount where Zakah becomes due.
Rest Allah knows best.
Source: Quran, Sunnah, Tafsir Ibn Kathir, In the shade of the Qur'an, An Explanation of the Last Tenth of the Noble Qur'an [Also with Critical Matters in the Life of a Muslim] Paperback – 2007; www.tafseer.info