Which of the following is considered a type of income for tax purposes?

Sales of property generate income from the transaction that must be reported on tax returns. When a property is sold, the seller usually receives money that can be categorized as a capital gain if the sale price exceeds the property's basis (the original cost plus any improvements made). This gain is considered taxable income under the Internal Revenue Code, meaning it has a direct impact on the taxpayer's overall taxable earnings for the year.

In contrast, an increase in property value is not recognized as income until the property is sold, hence it is not taxable until that point. Currency conversion gains may be subject to tax, but they generally fall under different rules regarding foreign currency transactions and are not as universally encountered. Loan proceeds are not considered taxable income because they represent borrowed funds that the borrower is obligated to repay, rather than earnings.

Therefore, sales of property are clearly identified as a type of income for tax purposes due to their definitive nature in generating taxable gains upon the transactions' completion.