Praise be to Allaah.

Firstly: 

The ruling concerning your registering the farm in your name although your father paid for it varies according to the reason for doing that. If you did that so as to ward off harm from yourselves, such as if there is an unjust law that forbids owning more than one farm, then it is permissible for you to do that, and there is nothing wrong with registering the farm in your name or someone else’s name. But if you did this in order to get rights to which you are not entitled, such as if the state stipulates that in order to get a farm for free or at a reduced price the applicant should not already have a farm, then what you did is haraam, and it is consuming people’s wealth unlawfully. 

If you want to set things straight – if the second scenario is the one that applies here – then you can buy the farm yourself, in a real sense, from your father, then it will be yours, or you can sell it and put things back as they were, which is that your father does not own a farm. 

Secondly: 

As for the ruling on lying about the real price of the farm in order to avoid paying taxes, this is permissible, because taking the people’s wealth by means of customs duties and taxes is haraam, so there is no sin on the Muslim if he tries to save his wealth from that. But whenever he can say things in a vague manner that may be interpreted in more than one way, that is better than lying. 

Ibn Hazm (may Allaah have mercy on him) said: 

(The scholars) are unanimously agreed that tolls that are charged on the roads and at the gates of cities, and the sales taxes charged in the marketplaces on the prices of goods that are brought in by ordinary people and merchants are a great wrong and are haraam and evildoing. End quote. 

Maraatib al-Ijmaa’ (p. 121). 

Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said when mentioning what the ruler may take: 

And a kind which it is haraam to take according to scholarly consensus … such as the mukoos (sales taxes) which is not justifiable at all according to scholarly consensus. End quote.  

Majmoo’ al-Fataawa (28/278). 

This is not one of the rights of the ruler, rather the one who calls it a right has fallen into a grave sin. 

Al-Nawawi (may Allaah have mercy on him) said: 

Something that is definitely forbidden and should be warned against is what the common folk and others like them say about these mukoos (sales taxes) that are taken from those who buy and sell and so on. They say that this is the right of the ruler, or that you have to give the ruler his due, and other such phrases which describe it as a right or duty and so on. This is a grave evil and one of the worst of newly invented things. One of the scholars even said that the one who calls this a right or duty is a kaafir who is beyond the pale of Islam! The correct view is that he is not a kaafir, unless he believes it is a right or duty even though he knows it is unjust. The correct wording is to call it a maks or tax imposed by the ruler, and other similar words. End quote. 

Al-Adhkaar (p. 369). 

See also the answer to question no. 39461 and 25758 and 42563. 

But if what is charged on transactions of buying and selling is ordinary fees for services rendered to the buyer or seller or both, then it is not permissible to try to evade them under any circumstances, rather this is a right that belongs to the one who takes it and it is not permissible to trick him and try to avoid giving him his dues. 

Thirdly: 

With regard to your question about zakaah on what the farm produces, it should be noted that zakaah is due from the real owner of the farm, which is your father in this case. 

In order for zakaah to be due on crops and fruits it is not essential that they be intended for sale, rather zakaah is due on them even if they are intended to be eaten by the owner and his children and family. 

Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) was asked: 

I have five date palms at my house, all of which bear fruit. Is any zakaah due on their fruit? What is the rate of zakaah? 

He replied: 

It is good that you have asked this question, because many people have houses where there are date palms, and the fruits borne by them reach the nisaab (minimum threshold), but they do not pay zakaah on it, because they think that zakaah is due from large plantations. As for date palms beside people’s houses, many people think that they are not subject to zakaah, but that is not the case, rather we say: If there are date-palms at your house and you have another garden, and the date palms at your house do not reach the nisaab, they should be added to the date palms that are in your (other) garden. 

But if you do not have a garden, then we look at the date palms that are at your house. If they reach the nisaab, then zakaah must be paid, and if they do not reach the nisaab, then no zakaah is due. 

The nisaab is three hundred saa’s of the saa’ of the Prophet (peace and blessings of Allaah be upon him) … 

To sum up: With regard to date palms at a person’s house, if the owner of the house has a garden in which there are date palms, the crop of the date palms at his house should be added to the crop of date palms in the garden. If the total reaches the nisaab, then zakaah must be paid. 

If he does not have a garden, then we look at the date palms that are by his house and we say: If their fruit reaches the nisaab, then zakaah must be paid on it, otherwise it may not. 

Zakaah is one-half of one-tenth on crops that are irrigated by artificial means and one full tenth on crops that are not irrigated by artificial means. End quote. 

Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen (18/question no. 39). 

There is a difference of opinion among the scholars concerning the crops on which zakaah must be paid. What we think most likely is that zakaah is due on crops which are measured and stored. See the answer to question no. 3593. 

And Allaah knows best.