Praise be to Allah.
It is haraam to deposit money in savings accounts, for two reasons:
1 – It is a contract that is based on adding a set percentage to the capital, whilst guaranteeing that the capital will remain intact. In fact it is an interest-based loan, and the scholars are unanimously agreed that every loan that brings a benefit is riba (usury). The lender here is the customer, and the borrower is the institution that provides these accounts.
Ibn Qudaamah (may Allaah have mercy on him) said: Every loan in which it is stipulated that more should be paid back is haraam, with no difference of scholarly opinion. Ibn al-Mundhir said: They are unanimously agreed that if the lender stipulates that the borrower must pay back more or give a gift, and he gives the loan on that basis, then this extra payment is riba. It was narrated that Ubayy ibn Ka’b, Ibn ‘Abbaas and Ibn Mas’ood forbade loans that bring benefits. (6/436).
2 – The Post office puts the money received into riba-based banks, and takes a set percentage for it, part of which it distributes as a reward to the depositors. This is another riba-based transaction that is done by the post office.
The post office borrows money with riba in the first case, and it lends money with riba in the second case. Hence the one who examines these transactions will have no doubt that they are haraam, and it is haraam to work in them whether as a scribe or witness or helping with it in any way.
In Mawsoo’at Fataawa al-Azhar, there is a question addressed to the former Shaykh of al-Azhar, Jaad al-Haqq ‘Ali Jaad al-Haqq (may Allaah have mercy on him) about the interest that is paid by banks or companies on the money that is deposited or invested with them – is this interest regarded as riba (usury) or not?
After mentioning the texts which forbid riba, he said: Based on these texts and others in the Qur’aan and Sunnah, all types and forms of riba are forbidden, whether it is additional to the amount that was originally lent, or an additional amount charged when payment is delayed, or this additional amount is stipulated in the contract along with a guarantee that the capital will remain intact. As that is the case, then the interest asked about, which is mentioned in the contract when depositing money in the bank, and in savings funds at the post office and banks, and in investment certificates which stipulate a specific return on the capital – the deposit in such cases is a loan with interest, and comes under the heading of riba al-fadl or riba al-ziyaadah, as the fuqaha’ call it. It is haraam in Islam, based on the general meaning of the verses in the Holy Qur’aan and the texts of the Sunnah, and the consensus of the Muslims. It is not permissible for a Muslim to deal in it or lend such loans, because he is responsible before Allaah for his wealth, from where he acquires it and on what he spends it, as it says in the hadeeth from the Messenger of Allaah (peace and blessings of Allaah be upon him) which was narrated by al-Tirmidhi: “A person’s feet will not move on the Day of Resurrection until he is asked about his life and how he spent it, about his actions and what he did, and about his wealth, from where he acquired it and on what he spent it, and about his body, how he used it.” And Allaah, may He be glorified and exalted, knows best. End quote.
Working in “entering all the receipts of deposits and withdrawals of customers to the main computer” comes under the heading of writing down riba. Muslim (1598) narrated that Jaabir (may Allaah be pleased with him) said: cursed the one who consumes riba and the one who pays it, the one who writes it down and the two who witness it, and he said: they are all the same.
What you must do is repent to Allaah, and hasten to give up this work, and move to another department that is far away from riba, or leave the work altogether, so as to get away from this grave major sin.
Remember that if a person gives up something for the sake of Allaah, Allaah will compensate him with something better than it, and that He will provide for the one who fears Him, and He will bless him and provide for him from sources he could never imagine.
“And whosoever fears Allaah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).
3. And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allaah, then He will suffice him. Verily, Allaah will accomplish his purpose. Indeed Allaah has set a measure for all things”
May Allaah help us and you to do that which is good, follow true guidance and attain success.
And Allaah knows best.