I am a long-time (15-year) renter in an apartment house. There have been yearly increases over the years but this year the owner wants a whooping 25% increase! Can this happen?

Your first step is to check your state landlord tenant law on rent increases for month-to-month tenancies. Unless the state or local law forbids rent increases without 60-day notice or limits the percentage increase, you have to pay the increased rent or move. You also want to make sure your landlord gave you adequate notice. The landlord has essentially terminated your old month-to-month agreement and is giving you the terms of a new agreement. If state law requires the landlord to give 30 days notice to terminate the agreement, and the landlord gave you less than 30 days notice of the rent increase, the notice is not effective until next month.