Proxy الحج for a living person is جائز when the person is permanently unable to perform الحج due to old age, incurable chronic illness, or permanent physical disability that prevents travel and performing the rites. This is directly أُسس by the hadith of the woman from Khath'am who asked النبي about performing الحج for her elderly father who could not sit firmly on a mount. النبي explicitly permitted it.
الشيخ ابن باز stated that the key condition is permanent inability. A person who is temporarily ill, temporarily financially constrained, or simply unable to travel this particular year should wait until they are able. Proxy الحج is not a convenience measure — it is a concession for genuine, permanent incapacity. He also clarified that the living person should fund the proxy's الحج from their own wealth.
Sheikh الفوزان addressed the question of what happens if the person unexpectedly recovers after proxy الحج has been performed. The majority of scholars hold that the proxy الحج is valid and the person does not need to perform الحج again, because the obligation was fulfilled through the proxy. The Maliki school, however, holds that if the person recovers and becomes able to perform الحج, they should perform it themselves, and the proxy الحج becomes voluntary. Sheikh الفوزان مستحب following the majority position that the proxy الحج fulfills the obligation.