Qurbani is Wajib on any major, sane Muslim, who is not a traveler and not indebt and who has wealth which equals the "Nisab" (required limit). For Qurbani to be Wajib, it is not necessary that 1 year should have passed on the wealth or that it should be of an increasing type. However, it is necessary for Zakaat.
If a person has apart from the basic necessities of life, 755 milligrams of gold or 425 grams and 285 milligrams of silver or is an owner of an equivalent amount of money or material possessions of that value, then that person is (Sahab e Nisaab) i.e. Qurbani is Wajib on that person.
The house which is used for living, the necessary things for the house, clothes, mode of conveyance (vehicle) are included in basic necessities. The Jurists (Fuqaha) have explained about clothes that 3 sets of clothes are included in basic necessities, one for use in the house, another for use at work, and a third one for use on special occasions like on Friday, Eid and the like. All other clothes are considered as surplus. About the house, it has been clarified that for every person of the house there should be 2 rooms; one for summer and one for winter. The kitchen, bathrooms, lavatories etc, are all included in basic necessities.
As has been given in Raddul Muhtaar, Vol. 5, Kitab Ul Uzhiyyah, pg no. 219.
In the light of the clarifications given by the Fuqaha, if the value of all other things, other than the basic necessities, amounts to the value of 60 gm and 755 mg gold or 425 gm and 285 mg of silver, then Qurbani becomes Wajib (compulsory) i.e. if there is a vehicle other than the necessary one, clothes more than 3 sets and other things beyond the basic necessities and the combined value of all these things reaches the aforementioned value of gold and silver, then Qurbani is Wajib.
Some people think that Qurbani is Wajib only on the head of the household, it is not necessary for others. Here it should be remembered that like Salaat, Fasts, Zakaat, Qurbani is also a worship, which is as per the aforementioned criterion, Wajib on everybody, irrespective of whether the person is the head of the household or not. If there are 5 people in a house who are eligible for Qurbani, then Qurbani is Wajib on each one of them.