Assalaamu alaykum wa rahmatullaahi wa barakaatuh. If one has not paid zakah in the past and must make up for all of them, is it possible for him to pay the old zakah based on the current amount of money in his possession? For example, the person has x amount of money and he multiplies the figure for the total of zakahs that he has to pay. Can one do this?Moreover, if I posses jewelry, gold and silver, but left it in my country and cannot return there, must I include it in the zakah? Moreover, I can not take my money that has been deposited. Can I take a loan in money from my husband to pay the zakah with the intention to return the sum of money to him? May Allaah bless you.

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

You asked, "Is it possible for him to pay the old zakah based on the current amount of money in his possession?" If you mean that he would pay the exact amount of the zakah on the current year for the past years as well; for example, if the due zakah in the current year is 100 riyals, he would pay 100 riyals for each of the past years (for which he failed to pay the due zakah), then you should know that this is incorrect, because the zakah on the past years may be greater than the amount of the zakah on the current year due to possessing more money then. However, if you know that you did not own more money subject to zakah in the past years, then there is no harm in paying the zakah on the past years equal to the amount of zakah on the current year.

Ibn ʻUthaymeen wrote about the person who did not pay his zakah in previous years, "He should estimate the amount of zakah the best he can, and Allaah does not burden any soul beyond its capacity. So, if it is ten thousand, for example, then how much is the zakah for one year? It is two hundred and fifty. If the amount of zakah is two hundred and fifty, then he should pay two hundred and fifty for each of the past years, unless he had more than ten thousand in some of those years, in which case he should pay extra."

As for the zakah on gold and silver jewelry, the Muslim woman is not obliged to pay zakah on her jewelry according to the view of the majority of the scholars. This is the scholarly view adopted at Islamweb. Please refer to fataawa 87362and 89106. 

There is no harm in borrowing money to pay the zakah on wealth kept with someone as a trust. You are not obliged to borrow money to pay the zakah in this case, but there is no harm if you borrow in order to pay it. You can also authorize the person you left your money with to pay zakah on it on your behalf; this is better than borrowing money to pay the zakah. The scholars stated that the individual should pay zakah on the funds kept with someone as a trust for all the years that they remain in his possession because the person to whom the funds are entrusted is authorized to act on behalf of the owner of the funds.

Ibn Qudaamah wrote:

"As for the wealth kept with someone as a trust, the same ruling of the wealth in his possession and at his direct disposal applies to such funds kept with someone as a trust because the entrusted person acts as an agent and holds broad authority to act on behalf of the owner in terms of preserving the wealth entrusted to him, and he is held in the same legal status as the owner of the wealth in terms of disposing of it. He should pay the zakah on the wealth kept as a trust because he owns it and can benefit from it. Accordingly, he is obliged to pay zakah on the wealth kept as a trust just like he is obliged to pay zakah on his other wealth..." [Al-Mughni]

Allaah knows best.