Social Security is paid in with after-tax dollars but may be subject to tax if annual income exceeds a base amount. A single taxpayer's base is $25,000. Married taxpayers filing jointly have a base of $32,000. Married taxpayers filing separately have a base of zero. Suppose Sean is retiring this year at age 67. The following table shows his data. Part-time salary $31,500 Annual savings account interest $275 Annual dividends $2,500 Annual interest on Denver municipal bonds $1,350 Based on the income calculated, Sean will have % of his Social Security benefits taxed