Rental increases - reasons?

[Jessica Stoneburner]

Hi BP forums!  New member here.  I'm not a typical "rental investor", merely a homeowner who has rented their property out for the first time, so this is my first (of many) questions.  

We recently moved out of our mortgaged home into a family-owned occupancy (to save money) and had decided on renting out the home instead of selling. We had a price set based on market value and had begun collecting interested parties (via a CraigsList posting) for when we were all moved out and the property was vacant. We had a great response. Unfortunately it did not work out that way as some "friends" were in need of a rental at the exact same time and could not afford our original price. We settled on a price $500 less than we had wanted, due to their financial situation (and our "friendship"), and signed a 1-year lease. We are now coming to the end of the lease and we want to increase the rent to the original amount we had determined to be FMV as well as what we personally needed to offset the mortgage/upkeep costs. I am not concerned about keeping the current tennants in the property, as even though we helped them out at a great financial cost to us, that friendship did not last. However, I do want to make sure we do things legally. I want to make sure our reasons for the increase are good enough (legally). Also, when I send the rent increase letter, do I have to include the reasons why we are increasing rent? I live in Ohio. Thank you for any insight.