We hear this question a lot in seminary classes. Consider the following scenarios:
1. Should you pay tithing on your gross income or on your net income?
2. If a neighbor gives you $20 to take care of her dog, should you pay tithing on that money?
3. If a neighbor gives you a T-shirt as a reward for taking care of her dog, should you pay tithing on the value of that T-shirt?
4. If you sell some stuff (like old skis) should you pay tithing?
5. If your grandmother mails you a birthday check of $20, should you pay tithing on it? Does your answer change if your grandmother is a tithe-paying member of the church?
6. If your grandmother buys you a cute hamster for your birthday, should you pay tithing on the value of the hamster?
Doctrine & Covenants 119:4 says that church members should give “one-tenth of all their interest annually.”
To help clarify, President James E. Faust said, “The law of tithing is simple: we pay one-tenth of our individual increase annually. Increase has been interpreted by the First Presidency to mean income. What amounts to 10 percent of our individual income is between each of us and our Maker. There are no legalistic rules” (James E. Faust, “Opening the Windows of Heaven,” Ensign, Nov. 1998, 59).
You need to decide for yourself what “income” means by prayerfully discussing the matter with the Lord. As President Faust said, what constitutes your income is between you and God.
President Faust in right on. (Duh.) As in most spiritual things (and all things are!) “increase” is SO between you and the Lord. He always, always knows your heart. If you give with pure intent, and with gratitude that you have increase to share with God and His children, you are on the right track!