Would Appreciate Some Advice

[Wade Garrett]

I just purchased my first fourplex and have a tenant who I foresee being an issue. 

She is currently on a month to month, as her previous lease with the old owner expired. The old lease says the rent was $900. Her security deposit is $900. There are payment receipts of $900. The tenant claims she is and has been paying $800. Market rent is $1,000. 

It sounds cut and dry when posted like that. But she also maintains the property in exchange for discounted rent. So I don't technically have to do much on a day-to-day basis. 

I am a little apprehensive about calling her bluff and calling her a liar right off the bat. Also, her residence in the place is fairly crucial to the investment. 

How do you recommend I handle her?

Thanks.