Tom and Ruth are both 68 and file a joint return. This year they receive 40,000 dollars of Social Security retirement benefits, 30,000 dollars of pension income and 4,000 dollars of tax-exempt municipal bond interest, and they have no other income. Assume provisional income is all other income including tax-exempt interest plus one half of the Social Security benefits, that the joint thresholds are 32,000 dollars and 44,000 dollars, and that the taxable portion is the lesser of 85 percent of the benefits or 85 percent of provisional income above 44,000 dollars plus the smaller of 6,000 dollars or one half of the provisional income above 32,000 dollars. How much of the benefits is included in gross income?
- A34,000 dollars, being 85 percent of the 40,000 dollars of benefits they received during the year
- B11,100 dollars, because tax-exempt municipal bond interest stays outside the provisional income figure
- C8,500 dollars, being 85 percent of the provisional income that sits above the 44,000 dollar upper threshold
- D14,500 dollars, being 8,500 dollars from the upper tier plus the 6,000 dollar lower tier addition Correct
Why A is wrong: This takes the ceiling on inclusion as though it were the answer. The 85 percent of benefits figure is only one limb of a lesser-of test, and here the other limb produces a much smaller number that governs.
Why B is wrong: Municipal bond interest is excluded from gross income but is added back when provisional income is measured, so leaving it out understates provisional income by 4,000 dollars and the inclusion by 3,400 dollars.
Why C is wrong: This computes the upper tier correctly but omits the lower tier addition, which brings in a further amount for the provisional income lying between the 32,000 and 44,000 dollar thresholds.
Why D is correct: Provisional income of 54,000 dollars exceeds the upper threshold by 10,000 dollars, giving 8,500 dollars, and the lower tier adds the smaller of 6,000 dollars and half of the 22,000 dollar excess over 32,000 dollars.