Legally, permission has to be given from the landlord before a sublease can be arranged. Some desperate college students might try to find a subleaser without letting the landlord know. To prevent a potential problem, subleasers should talk to the landlord and confirm approval. Some landlords will not allow subleasing to occur. Others will allow leasing but under strict conditions, while others have no problems with it.
A problem may arise when a subleaser assumes he will be living alone in the apartment or looks for roommates and there are already people living there. To avoid surprises for both you and others who may already be living in the apartment, it's advisable to double-check who will be living there and meet the roommates ahead of time.
By law, the person originally on the lease is responsible for the rent. If the subleaser does not pay his portion of the rent, the original tenant could be fined, billed for the rent or even sued. The same type of problem could happen to the subleaser if he is sharing a portion of the rent with the original tenant. If the original tenant fails to pay her portion of the rent, the subleaser could get evicted. Documenting everything in a leasing agreement that details who pays what is a way to possibly avoid this situation.
If the original tenant fails to turn off utilities, cable television and Internet registered in his name, the subleaser could take advantage of the situation and use them without paying. If this should happen, the original tenant would then be stuck with the bills.
If the original tenant finds someone to sublease her apartment, she is still responsible for any damage done at the end of the lease. The subleaser could do all sorts of damage to the apartment and not have any repercussions, while the original tenant does not get her security deposit back and gets a bad reference.