What Counts as Rental Income?
Anytime someone else pays you to use or occupy your property, that's rental income. And yes, we mean anytime. Unless you rent your property for less than 15 days in a given year, you'll need to include all of the following forms of passive rental income in your gross income and report it on IRS Form 1040 Schedule E to avoid running afoul of Uncle Sam.
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Even if your tenant gives you an advance rent payment for a subsequent year, you must include it in your gross income in the year you receive it.
Source Fool.com