I think I solved my own problem. I am on Social Security, and I had used the 85% amount being taxed on my spreadsheet. I believe that ALL income before ANY deductions goes into the Gross amount that the IRS uses to determine whether you pass the limit. It seems that if dividend/CG amounts cause the Gross to exceed the limit by even $1, none are eligible for the 0% taxable rate.
I guess that's the danger of doing the calculation on a self-made spreadsheet. Now I have to figure how Minnesota taxes Social Security!
