The purpose of signing a lease on an apartment is so that the the rent is "frozen" for the term of the lease. What the rental company gets out of the deal is a commitment from you to stay in the apartment for the term of the lease. After the lease expires, the rental company can raise the rent every month if they like, as long as they give you thirty days notice before. Of course, you can also leave the premises, as long as you give them thirty days notice of your intentions. You might negotiate with the rental company to prevent this. For instance, if you know you want to stay in your apartment, you might ask if you can sign another lease at the lower rent rate. Since that guarantees that they will have a tenant in the apartment (and thus money coming in), they might be amenable. Be aware that you are then obligated to stay in the apartment for however long you have agreed to.

The short answer is yes. This depends on a lot of factors: the laws applicable where you reside and if you are in a rent controled area. Rent control, the short version, is a mechanism that allows you to lease a property at the initially stated rent continously provided you do not break the lease. Rent control laws vary widely. Some jurisdictions cap the amount a landlord can increase the rent annually or at lease renewal time in terms of a number that is usually expressed as a percentage. When I rented, the rent increased an average of 10-15% per anum. Which is high compared to the national average which, at last check, fell between 5-7%. How do they justify it? Many ways. Increased costs to mainatin the property, upgrades in services (gym, pool, etc.), market conditions, etc. My favorite "excuse" was that they had taken harder hits on subsidized (Section 8) housing requirements. Where I live, apartment complexes are legally required to allot "X" number of units as subsidized. I paid $1800 per month for a tiny one bedroom and the 3 bedroom unit a few rows down was rented to a welfare recipient for half that. Galling to say the least. And mid-lease they stuck me with paying for water too. Rent may also be increased, if the lease is written in such a manner, for "additional charges". For example, if you have a pet, the "pet rent" may go from $20 to $30 per month. Or utilities that were once included in the rent now have to be paid by you. The lease term does not have to be up to tack on these charges. However, mosts states require that the landlord notifies you of any mid-lease changes in writing. And most reputable landlords do in fact wait until the lease is up as a courtesy to the renter. I tried negotiating the terms of my lease renewal and I made the request in writing. I pointed out that I had been a solid renter for 3 years, had never paid late, and had no complaints filed against me. No dice. I moved. Give it a shot, you might have better luck than I did.