Hajj becomes wajib on anyone who fulfills the following requirements:
1. Is baligh.
2. Has enough time to go to Makkah and perform all the rites of Hajj.
3. Has enough money for travel and other Hajj related expenses. Example: Food, accommodation, qurbani, etc.
4. Should have enough money to give to his dependents so that they can meet their requirements until his return from Hajj.
5. Security i.e. there should be no danger to the pilgrim's life, wealth or honor throughout the journey.
6. Should be healthy enough to perform all the rites of Hajj. He should not have such an illness or weakness that he cannot bear the difficulties of the journey.
7. On return from Hajj he should be able to earn for himself and his dependants.
Hajj will also become wajib if someone else gives you money to meet your Hajj expenses and once you've performed such a Hajj, Hajj will never be obligatory upon you ever again, even if at a later date you are financially able to perform Hajj yourself. Example: A father pays for his baligha daughters' Hajj expenses.
If a person has taken a loan and the loan repayment date has not yet arrived but he has now got enough money to meet Hajj expenses he will first perform Hajj and later repay the loan. Simply being in debt does not waive Hajj.
If a person has some property or assets that are above his social standing, it is wajib upon him to sell them and meet his Hajj expenses.
If a lady has more jewelry than her social standing allows her to keep or she has become so old that she does not need her jewelry she must sell her jewelry and use the money to go for Hajj. Similarly if the lady has enough meher money to meet her Hajj expenses and it is possible for her to obtain her meher then it is wajib for her to demand her meher and go for Hajj.
If a person has only so much money that if he pays the zakat which are wajib on him he will not have enough money remaining for Hajj, then it is wajib upon him to pay the zakat and Hajj will no longer be wajib on him.
If someone is so old or weak that he cannot bear the difficulties of Hajj, then Hajj is not wajib on him. But if Hajj was previously wajib on him and in spite of having the ability he had not performed it, Hajj has to be performed in whichever way possible even if he is now old or weak. And if he is completely unable to perform Hajj then during his lifetime he should send someone else to perform Hajj on his behalf and if this is not possible he should make a will in this regard.
If Hajj becomes wajib on a person and he dies, Hajj expenses must be set aside from the wealth he leaves behind. Without removing this sum, distributing his wealth is haraam and a sin.
When Hajj becomes wajib, it is wajib to discharge the duty immediately i.e. in the same year. It is not allowed to postpone it.