Retirement Contributions and Distributions Question 18 of 75. Joel (69) and Carl (67) are married. They filed separate returns and lived apart most of the year. Joel's gross income (including 1/2 of his social security) for 2019 was $23,000. Up to ___ of Joel's social security benefits may be taxable. 0% 50% 85% 2 O 100% Mark for follow up