"At the end of three years, you shall bring forth all the tithes of your produce"—Deuteronomy 14:28.

We are commanded to separate a tenth of our harvest [in addition to the First Tithe given to the Levites] on the third and sixth year of the seven-year Shemitah cycle, and give it to the poor.

[During these two years, this tithe substitutes the Second Tithe.]

This biblical precept only applies in the Land of Israel.