Is it permissible for a working couple to save money for the Hajj pilgrimage?

Hajj is obligatory only upon those who are able, as Allah Almighty says: "And [due] to Allah from the people is a pilgrimage to the House - for whoever is able to find thereto a way." (Quran 3:97). Saving extra money beyond one's needs for Hajj is a good thing, but it is not obligatory. Nor is it obligatory for the poor person to earn money specifically for Hajj. If a person has a characteristic that enables him to acquire, after a period, what would make him able to perform Hajj, by saving daily what is surplus to his sustenance and needs, he is not obligated to do so. He may instead give in charity what is surplus to his sustenance and needs.