Ok I tested it. You get 0 on 6b if you didn't answer the Foreign question right. But since you have an amount on 6b then it not for the Foreign question. So the IRS must have increased some other of your income.
As I said.....Like the taxable amount of a 1099R you got or you missed entering some income. Like if a 1099R got entered on the wrong line 1040 line 4 or 5, the IRS would miss it and think you didn’t report it. By increasing your other income it made more of your SS taxable. Oh, is the full amount of your SSA-1099 in box 6a?
