Raising Rent or Notice to vacate

[Samuel Cardenas]

So, I'm purchasing my first piece of rental property and the rent in the neighborhood is starting  $1,100. The current tenants are paying under market value at $850. They are on month to month with no contract and I want to give the option to pay the $1,100 or vacate with a 30 day notice. How do I properly go by doing this? what Paperwork is needed? This is in Illinois, and I close Friday!

Thank you guys in advance!!