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.
Source: Getty Images
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