Thanks for asking your question! I'm sorry to hear about your tax issue and I'm going to try my best to help you understand or resolve it.
Thank you for your question, and thanks for using JustAnswer.com. Even though you may have taxable income on lines 20 a &b you might still owe no tax. This is your income before deductions
, so you could have no taxable income once you take your deductions and exemptions. This is probably why you had taxable income on line 20b, yet did not owe tax at the end of the year.
So, the reason you had no tax is your deductions and exemptions. These were equal to or greater than your social security income. This made your taxable income 0. Please let me know if you need anything additional. Thanks again for using JustAnswer.com and have a great day.
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You should be aware that your question, as with most tax questions, can never really be answered completely...addressing all the permutations; that is because of the many assumptions that have to be made I have done my best to determine what I think you are asking and answering it in the most direct and understandable manner possible. If, however, after reviewing the questions, you have any uncertainties or further questions, please do not hesitate to ask.