This is a matter of scholarly disagreement. The question is whether the obligation of Hac is 'immediate' (fawri) — meaning it must be performed at the first available opportunity — or 'deferred' (ala al-tarakhhi) — meaning it can be delayed to a later year without sin. Both positions have supporting evidence.
Sheikh Ibn Baz held the position that Hac is an immediate obligation. Once a Muslim has the physical ability, financial means, and all conditions for Hac are met, they must perform it at the earliest opportunity and should not delay without a valid excuse. He cited the hadith: 'Hasten to perform Hac (the farz one), for none of you knows what may happen to him.' Delaying without excuse is sinful because the person cannot guarantee they will be alive or able next year.
Sheikh Al-Fawzan agreed that the stronger position is immediate obligation, stating that a person who has the means should not procrastinate. He noted that many Muslims delay Hac year after year despite having the ability, and this is a serious matter. If a person delays and then loses the ability (due to illness, financial loss, or death), they bear the sin of having neglected an obligation. He also noted that the Shafi'i position, while valid, carries the risk of a person continually postponing until it becomes too late. The safer approach is to perform Hac as soon as one is able.