He has money, land and a business partnership with his friends and is asking how to pay zakah on them

Firstly:

We ask Allah to accept your righteous deeds from you, and to help you and guide you.

You should understand that zakah is an act of worship and you should not have delayed it from the time when it was due, except in the case of a pressing excuse or a legitimate (shar‘i) reason that forces you to delay paying it.

Ibn Qudaamah (may Allah have mercy on him) said:

zakah must be paid as soon as it becomes due, and it is not permissible to delay paying it when one is able to do pay it, so long as there is no fear of harm. This is the view of ash-Shaafa‘i.

If he delays it in order to pay it to someone who is more deserving of it, such as a relative or one who is in desperate need, then if it is a small amount, there is nothing wrong with that, but if it is a large amount, that is not permissible.

Al-Mughni (2/539).

Hence what you should have done is to hasten to pay the zakah of your wealth, and not delay that. May Allah pardon us and you, and forgive us and you. We advise you to hasten to pay it, and we hope that you did not delay paying zakah in order to pay it in Ramadan. You should note that there is no virtue in paying zakah in Ramadan. We have discussed this issue in the answer to question no. 13981.

Secondly:

You have to pay zakah on your wealth that has reached the minimum threshold (nisaab) set by Islamic teachings, which is equivalent to the value of 595 grams of silver, when one full Hijri year has passed since acquiring it. So you should pay zakah on this wealth when one full year has passed, and on any profits that have resulted from this wealth. As for any other increase in your wealth for some other reason, such as a salary, then that is to be worked out separately (when one year has passed since acquiring it). The best is to give zakah on all of your wealth, whether it increased because of investing the capital (in business and so on) or it increased by other means. You can find details of that in the answers to questions no. 100570, 50801 and 93414. The rate of zakah is one quarter of one tenth (2.5%).

If you choose to give zakah on all of your wealth, then the details of that are as follows:

1. The zakah of 3,150 riyals is 78.75 riyals.
2. The zakah one your share of the business with your friends is: for each thousand riyals, 25 riyals, but it is not based on the production cost of the goods; rather it is based on their market value at the time when zakah becomes due, as we have explained in many answers. See, for example: 65722 .
3. No zakah is it due from you on the value of the land if it is not prepared for sale. But if you buy and sell land, and this land is part of your trading business, then you must give zakah on its market value at the time when zakah becomes due, which is the twenty-fifth of Ramadan. It is not stipulated that it be sold in order for zakah to be due on it; rather it is sufficient that you have taken it as something to be traded. zakah must be paid on its value at a rate of twenty-five riyals per thousand riyals.

See also the answers to questions no. 32715, 67594 and 105334.

Thirdly:

There is no need to separate your business with your partners and your personal wealth when it comes to zakah; rather it is sufficient to add what you have of personal wealth and personal business to what you possess in partnership with others, and give zakah on the total.

Fourthly:

If you do not have enough cash to pay zakah on your business and your land, then it is a debt that you owe and must pay off when you are able to do that. It is permissible for you to borrow money in order to pay zakah, but it is not obligatory to do so.

The scholars of the Permanent Committee were asked:

There is someone who owns land the value of which is, for example, 100,000 riyals, and it is for sale. One full year has passed since he acquired it, and the owner does not possess anything else. Can he borrow money from people in order to pay zakah on it, or can he pay the zakah on it for past years after he sells it, as some people say? If he pays zakah for several years after selling it, how should he work out its value for each year, because the value fluctuates?

They replied:

The value of this land should be worked out every year, then if he has enough cash to pay zakah every year, he should pay it. If he does not have anything with which to pay zakah, he is not obliged to borrow money in order to pay zakah, but if he does borrow money to pay zakah, that is permissible. If he does not borrow money, then the zakah remains something that he owes, and he must pay zakah on past years when he sells the land or when he has enough money to pay the zakah on it.

Shaykh ‘Abd al-‘Azeez ibn Baaz, Shaykh ‘Abd ar-Razzaaq ‘Afeefi, Shaykh ‘Abdullah ibn Ghadyaan

Fataawa al-Lajnah ad-Daa’imah (9/327, 328)

See also the answer to question no. 47761.

And Allah knows best.