Short Answer
If you owe someone money, and that money is due now, you subtract it from the amount of wealth you possess when deciding whether or not you have the means to perform Hajj. It is necessary to pay off your debts which are currently due, unless the creditor gives you an extension. However, if it is a long term loan such as a student/house/car loan with monthly payments, then you will only subtract the current installment that is due now when determining whether you can afford to undertake the journey of Hajj.
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Shaykh Mustafa Umar