Why is a term of years, rather than the lives of the income beneficiaries, used in a Charitable Remainder Trust?

A term of years is generally used to accentuate the current income tax deduction. For example, an unmarried taxpayer who has a substantial unplanned taxable windfall may wish to generate enormous current income tax deductions and still benefit charity. A term of years is also used to have a higher supplemental income fill an income shortage during a particular gap of years. For instance, if you wanted to take early retirement at age 50 and needed to generate additional income for a 10-year period before taking retirement funds from your pension, you could establish a Charitable Remainder Trust with a 10-year payout term to supplement your income until age 60.