Amelia owns a 1/4 royalty interest in a uranium mine. Amelia has the owner of the mine pay 1/3 of her royalties to her neighbor, Joel. During the current year, Amelia receives $18,000 and Joel receives $9,000 in royalty payments. Amelia has $27,000 of gross income from the royalty payments. Joel has no income. What concept is primarily responsible for this treatment?

Natalie is an accrual basis taxpayer. A renter pays Natalie the January 2023 rent in December 2022. Natalie must recognize rent income for tax purposes in 2022. Which concept is primarily responsible for the tax treatment?

Larry bought 300 shares of Shamrock Common Stock in April for $6 per share. At December 31, Shamrock Common Stock is selling for $8 per share. Larry does not have to recognize any income from the Shamrock Common Stock in the current year. What concept is primarily responsible for this treatment?