When you invest in many types of real estate and equity crowdfunding offerings, what you’re actually receiving is not a direct ownership stake in the property or company, but rather a membership interest in a “special purpose vehicle” (SPV) set up for the investment, usually an LLC (though sometimes a Limited Partnership or other entity).
Schedule K-1 is the IRS form you’ll typically receive at tax time, which indicates any income (for example from interest payments or rental income) that you received from the SPV. The K-1 will also show what percentage ownership you have in the SPV.
In the case of some equity investments, you may receive a K-1, but it won’t report any income until/unless there’s some form of liquidity event like an acquisition. The IRS has more information on Schedule K-1, or you may wish to ask your tax professional for more details on the tax implications of investment crowdfunding on your particular situation.