Is it permissible to stipulate that the borrower must pay the difference in value if the currency drops?
Question

                I am student in a British university. As a British student, the government here gives me a loan to complete my study. This loan is not interest-based, as it is mentioned in the terms and conditions. It will be also considered cancelled after 25 years of taking it. It must not be paid unless the student starts working with a salary of at least 15 000 pound a year. But it includes what is called inflationary interest, meaning that if the currency price drops by 0.01%, then I will have to pay this difference. 

I have asked a lot, many fatwa councils in Europe said that it is permissible loan, as well as many scholars did. But some scholars said it is haram, I do not know what to do?.
Praise be to Allah.It is not permissible for 
    the one who borrows money from anyone to commit himself to repaying the loan 
    based on the value of the currency at the time when the loan is repaid, 
    rather he must repay the loan with the same value as it had at the time he 
    took it. This is the view of the majority of scholars both classical and 
    modern, and it is what is stated in fatwas issued by contemporary fiqh 
    councils. This applies if the currency remains in circulation, even if the 
    exchange rate changes. 
But if the currency is 
    abolished altogether and the people no longer use it, in this case there are 
    different scholarly opinions. 
Some scholars say that the 
    borrower must pay back the value at the time of the loan. 
Some say that what counts 
    is its value at the time the currency is abolished. 
Others say that what 
    matters is its value at the time of paying it off. 
Shaykh Muhammad ibn Saalih 
    al-‘Uthaymeen (may Allaah have mercy on him) said: 
The view that is most 
    likely to be correct is the view that what counts is the value at the time 
    the currency is abolished, because he was responsible to pay ten fuloos [a 
    kind of currency] until it was abolished, i.e., if he had asked him for ten 
    fuloos one minute before it was abolished, he would have given him ten 
    fuloos, and it would have been binding on the lender to accept it. So if 
    that is the case, we should estimate the value to be paid at the time when 
    it is abolished. End quote.  
Al-Sharh al-Mumti’ 
    (9/104). 
This is the ruling in the 
    case of the currency being abolished and another being used instead. But if 
    the currency is still valid and people are still using it, then it must be 
    repaid as it is, even if the rate of exchange is different and even if the 
    purchasing power has changed, and even if there is inflation. This is stated 
    in a report by the International Islamic Fiqh Council which belongs to the 
    Organization of the Islamic Conference, which is sufficient and good. 
Statement no. 115 (9/12) 
Re: 
Inflation and change in 
    currency values 
The Journal of the 
    International Islamic Fiqh Council which belongs to the Organization of the 
    Islamic Conference in its eighteenth session held in Riyadh, in the Kingdom 
    of Saudi Arabia, 25 Jumaada al-Aakhirah  – 1 Rajab 1421 AH (23-28 September 
    2000 CE). 
After studying the closing 
    statement of the Economic Fiqh Council for the Study of Inflation (in its 
    three sessions in Jeddah, Kuala Lumpur and al-Manaamah) and its 
    recommendations and suggestions, and after listening to the discussions on 
    this topic with the members and experts of the Council and a number of 
    fuqaha’, the following has been determined: 
1 – Affirmation of the 
    previous decision, no. 42 (4/5) which reads as follows: 
“What matters with regard 
    to repayment of undisputed debts in a certain currency is that they should 
    be paid in the same currency, not the equivalent value, because debts are to 
    be paid off in the same form as the loan was given. It is not permissible to 
    connect debts owed, regardless of the nature of the debt, to changes in the 
    level of prices.” 
2 – In the event that 
    inflation is expected at the time of signing the contract, the contract may 
    be drawn up based on a currency or form of wealth other than that which is 
    expected to fall, such as basing the contract on the following: 

    (a)Gold or silver

    (b)A similar product

    (c)A basket (group) of similar 
    products

    (d)Another, more stable currency

    (e)A basket (group) of currencies
Payment of the debt in the 
    examples given above must be in the same form as that on which the loan was 
    given, because the borrower is not obliged to pay back anything more than 
    what he actually received. 
These cases are different 
    from the case which is forbidden, whereby the two parties involved in the 
    transaction do the deal on the basis of giving in one currency on condition 
    that the debt is paid back in another currency or a basket (group) of 
    currencies. The prohibition on this type of loan was issued in the Council’s 
    statement no. 75 (6/8). 
3 – It is not permissible 
    in sharee’ah to agree when drawing up the contract to connect payment of the 
    debt to any of the following: 

    (a)a mathematical formula

    (b)the index of living expenses or 
    any other index

    (c)gold or silver

    (d)the price of a specific item

    (e)the average gross domestic 
    product

    (f)another currency

    (g)the rate of interest

    (h)the average price of a basket 
    (group) or products
That is because this kind 
    of connection may lead to many types of risk and unknown factors, to such an 
    extent that neither party knows what is owed or expected to be paid, so the 
    condition of clarity which is required for contracts to be sound will not be 
    met. 
If these things to which 
    the debt is connected increase in value, that will result in differences 
    between what is owed and what is expected to be paid, and if the contract is 
    based on that, it is riba.  
This statement by the Fiqh 
    Council is in accordance with that which was stated in fatwas by the 
    Standing Committee, Shaykh ‘Abd al-‘Azeez ibn Baaz, and Shaykh Muhammad ibn 
    Saalih al-‘Uthaymeen (may Allaah have mercy on them). 
The Standing Committee for 
    Issuing Fatwas said: 
The borrower must pay the 
    pounds that he borrowed at the time when the lender asks for them, and the 
    difference in purchasing power does not affect anything, whether it has 
    increased or decreased. 
Fataawa al-Lajnah 
    al-Daa’imah (14/146). 
See also the answer to 
    question no. 23388, as it 
    deals with a similar question. The two answers complement one another. 
And Allaah knows best.