(According to the Qur'an and Sunnah, as extracted and inferred by scholars of the Hanafi school.)
From "Mukhtasar al-Quduri", a matn of Hanafi fiqh

1.0 OBLIGATION

1. Zakat is obligatory on
   

   	the free, adult sane Muslim,
   	when he possesses the nisab with complete possession, and
   	a [lunar] year has passed over it.

   There is no zakat [obligatory] upon a child, nor an insane person, nor a mukatib.

   There is no zakat [obligatory] upon anyone who has a [due] debt encompassing his money. But, if his money is more than the debt, he pays zakat on the excess if it reaches nisab.

   If one advance-pays the zakat before the year [has passed over it], and he possesses nisab, it is valid.

   If wealth is destroyed after the obligation of zakat [has become due], it is waived.
   

2. [Zakat due (in various proportions) on : gold silver cash trade-goods freely-grazing livestock kept for milk, breeding or fattening : camels, cows, sheep and goats. produce (excluding firewood, reeds and grass). buried treasures and metals.]

   There is no zakat [obligatory] on:
   

   	residential homes,
   	body clothes,
   	household furniture,
   	riding-beasts,
   	slaves in service,
   	weapons of use.

3. It is not valid to offer zakat without an intention coinciding with the payment, or coinciding with the setting-aside of the obligatory portion.

   One who gave all of his wealth in charity, without intending zakat, its obligation is waived from him.

2.0 ZAKAT ON SILVER

1. There is no charity [obligatory] on any [silver]less than 200 dirhams.
   [200 dirhams corresponds to19.69 troy oz and 612.36g.]
   
2. Then, if it is 200 dirhams, and a [lunar] years passes over it, 5 dirhams are are due for it.
   
3. There is nothing due on the excess until it reaches 40 dirhams, and then 1 dirham is due for it.
   [Similarly] for every 40 dirhams, there is 1 dirham [due].
   Abu Yusuf and Muhammad said : Whatever exceeds 200 [dirhams] its zakat is in proportion.
   
4. If the silver is dominant in silver coins, then their ruling is that of silver. But, if alloy is dominant then their ruling is that of trade goods, and its reaching nisab is taken into account.

3.0 ZAKAT ON GOLD

1. There is no zakat [obligatory] on any gold less than 20 mithqal.
   [20 mithqal corresponds to 2.81 troy oz and 87.48g.]
   
2. Then, if it is 20 mithqal, and a [lunar] year passes over it, then half a mithqal is due for it.
   
3. Then, for every 4 mithqal, 2 qirat [are due].
   There is no charity [obligatory] on any [gold] less than 4 mithqal according to Abu Hanifah.
   
4. There is zakat due on raw gold and silver, [as well as on] jewelry and vessels [made] of them.

4.0 ZAKAT ON GOODS

1. Zakat is obligatory on trade goods, whatever they may be, if their value reaches the nisab of gold or silver; one assesses it based on whichever of the two is more beneficial for the poor and destitute.
   
2. If the nisab is complete at teh two ends of the [lunar] year, then its dropping in between that does not waive the zakat.
   
3. The value of goods is added to gold and silver.
   Similarly, gold is added to silver in value in order to reach the nisab, according to Abu Hanifah. Abu Yusuf and Muhammad said : Gold is not added to silver by value, but it is added by parts.

5.0 THOSE TO WHOM IT IS AND IS NOT ALLOWED TO GIVE ZAKAT

5.1 Those Who May Receive Zakat

Allah, the Exalted, says, (translated),

"Alms are only for the poor, the destitute, those who collect them, those whose hearts are to be reconciled, for [mukatib] slaves, debtors, and in the Path of Allah, and the wayfarer. An [ordained] obligation from Allah. And Allah is Knowing, Wise." [Qur'an, 9:60]

These, then, are eight categories, out of which ‘those whose hearts are to be reconciled' have dropped, because Allah has granted honor to Islam and has freed [it] of need of them.
The Poor : is one who has the least of things.
The Destitute : is one who has nothing.
The [Zakat-]Worker : is paid by the imam in proportion to his work, if he worked.
Slaves : the mukatibun are assisted in freeing themselves.
The Debtor : is one on whom a debt is incumbent.
In the Path of Allah : are the stranded fighters.
The Wayfarer : is one who has money in his home-land, but is in a place in which he has nothing.
These, then are the sections of zakat.
The possessor may pay [some] to each of them, or he may restrict himself to one category.

5.2 Causes Not Eligible for Receipt of Zakat

1. It is not permissible for one to give zakat to a dhimmi,
   
2. Nor may a mosque be built with it,
   
3. Nor may a dead person be shrouded with it,
   
4. Nor may a slave be bought with it to free,
   
5. Nor may it be payed to a rich person.

5.3 Relationships Making One Ineligible to Receive Zakat

1. Nor may the payer of zakat pay it to his father, nor his grandfather even if higher [up in ascendancy],
   
2. Nor to his child, nor his child's child, even if lower [down in descendancy],
   
3. Nor to his wife.
   A woman may not pay [her zakat] to her husband, according to Abu Hanifah. Abu Yusuf and Muhammad said : she may pay [it] to him.
   
4. One may not pay [one's zakat] to one's mukatib or slave, nor to the slave of a wealthy person, nor to the child of a wealthy person if he is a minor.
   
5. It may not be paid to Banu Hashim, and they are : the Household of `Ali, the Household of `Abbas, the Household of Ja`far, the Household of Harith ibn `Abd al-Muttalib; nor to their freed slaves.

5.4 Miscellaneous Regulations

1. Abu Hanifah and Muhammad said : If one pays zakat to a man whom one thinks to be poor, and then it transpires that he is rich, or Hashimi, or an unbeliever, or [if] one paid [it] in darkness to a poor person, and then it transpired that he was his father or his son, then repeating it is not [obligatory] upon him.
   Abu Yusuf said : Repetition is [obligatory] upon him.
   If one paid [it] to a person, and then he learned that he is his slave or mukatib, it is not valid according to the verdict of them all.
   
2. It is not permissible to pay zakat to anyone who possesses the nisab of whatever type of wealth it may be. It is permissible to pay it to anyone who possesses less than that, even if he is healthy and earning.
   
3. It is disliked to transfer zakat from one land to another; rather the alms of each people should be distributed amongst them, unless a person transfers it it to his relatives, or to a people who are more in need than the people of his land.

6.0 SADAQAT AL-FITR

6.1 Obligation

1. Sadaqat al-Fitr is wajib on the free Muslim, if he is in possession of the quantity of nisab in excess of his dwelling, clothing, furnishings, horse, weapons and service slaves.
   
2. He gives it out on behalf of himself, his minor children and his slaves.
   He does not pay [it] on behalf of his wife, nor his adult children, even if they are in his household.
   He does not give it out on behalf of his mukatib, nor his slaves [who were acquired] for trade.
   There is no fitrah due on either of the two [masters] of a slave [co-owned] between two partners.
   A Muslim master pays the fitrah on behalf of his unbelieving slave.
   
3. The obligation of the fitrah is attached to the rise of the dawn on the Day of [`Id al-] Fitr. So, whoever dies before that, his fitrah has not become wajib. Whoever accepts Islam, or is born, after the rise of the dawn, his fitrah has not become wajib.

6.2 Payment

1. The fitrah is :
   half a sa` of wheat, OR
   one sa` of [dried] dates or raisins or barley.
   The sa` according to Abu Hanifah and Muhammad is 8 Iraqi ratl.
   Abu Yusuf said : [it is] 5<sup>1</sup>/<sub>3</sub> ratl.
   [1 sa` is a volume of 2.03 litres, and corresponds to approximately 3,149.28g.
   1 sa` ~ 4 mudd; 1 mudd ~ 2 ratl; 1 ratl ~ 20 istar; 1 istar ~ 4½ mithqal {Radd al-Muhtar}]
   
2. It is recommended for people to give out the fitrah on the Day of Fitr before going out to the prayer place. If they advance-pay it before the Day of Fitr, it is valid. But, if they delayed it beyond the Day of Fitr, it is not waived, and it is [still an obligation] upon them to give it out.