Is it permissible to take a loan from the British government to cover study expenses, knowing that it is waived after 25 years and is only repaid when income exceeds £15,000, and it includes an inflation rate that compensates for the devaluation of the currency?

It is not permissible for someone who has borrowed money to commit to returning its value at the time of the loan. Rather, they must repay the loan with the equivalent of what they took, as long as the currency is in circulation, even if its exchange rate or purchasing power changes. This is the opinion of the majority of scholars and the resolutions of Islamic Fiqh academies.

However, if the currency is abolished entirely, scholars have different opinions regarding what is considered: some said the value at the time of the loan, some said at the time of prohibition [of the currency], and some said at the time of repayment. Sheikh Al-Uthaymeen preferred that what is considered is the value at the time of prohibition.

The International Islamic Fiqh Academy has affirmed that the consideration in repaying fixed debts in a certain currency is by its equivalent, not by its value, and it is not permissible to link fixed debts to the price level. One can hedge against expected inflation at the time of contracting by having the debt in a currency not expected to depreciate, such as gold, silver, a fungible commodity, or another more stable currency. The repayment of the debt must be in the equivalent of what the debt was contracted in. It is not permissible to agree, at the time of concluding the contract, to link deferred debts to any index or other currency, due to the presence of gharar (uncertainty) and jahalah (ignorance) in that.