I'd recommend you use an online tax calculator to see the effect it will have. To your comment with @littleadv, there's FMV, agreed, but there's also a rate below that. One that's a bit lower than FMV, but it's a discount for a tenant who will handle certain things on their own. I had an arm's length tenant, who was below FMV, I literally never met him. But, our agreement through a realtor, was that for any repairs, I was not required to arrange or meet repairmen. FMV is not a fixed number, but a bit of a range.
If this is your first rental, you need to be aware of the requirement to take depreciation. Simply put, you separate your cost into land and house. The house value gets depreciated by 1/27.5 (i.e. you divide the value by 27.5 and that's taken as depreciation each year. You may break even on cash flow, the rent paying the mortgage, property tax, etc, but the depreciation might still produce a loss. This isn't optional. It flows to your tax return, and is limited to $25K/yr. Further, if your adjusted gross income
is over $100K, the allowed loss is phased out over the next $50K of income. i.e. each $1000 of AGI reduces the allowed loss by $500. The losses you can't take are carried forward, until you use them to offset profit each year, or sell the property.
If you offer numbers, you'll get a more detailed answer, but this is the general overview. In general, if you are paying tax, you are doing well, running a profit even after depreciation.