حج is not واجب if debts prevent financial ability, but if you can maintain payments while affording حج, many scholars permit it — seek creditor permission when possible.
The question of حج with debts requires careful consideration of the Islamic principle of istita'ah (ability), which is a condition for حج to become واجب. The majority of scholars across all four madhahib agree that if a person has debts that prevent them from meeting their financial obligations, حج is not yet واجب for them — they should prioritize debt repayment. The rights of creditors are a serious matter in Islam.
However, the situation is more nuanced for people with long-term structured debts (mortgages, student loans, installment plans). If you can afford the حج expenses while maintaining your regular payment schedule without defaulting, many contemporary scholars permit performing حج. The Hanafi position tends to be more flexible on this, while the Hanbali position is stricter about clearing debts first. It is strongly مستحب to seek written permission from creditors and to make a written will before traveling in case anything happens. For voluntary (nafl) حج — meaning you have already performed your واجب حج — scholars unanimously advise paying off debts first.
Source: Ibn Qudamah, al-Mughni; al-Nawawi, al-Majmu'; al-Kasani, Bada'i al-Sana'i