Social Security
What usually happens is the IRS changed some other income on your return. 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.
Or There is a new question this year asking if you lived in a foreign place. People have been answering it wrong or skipping it. Go back through the Social Security entries.
TAX Line 16
Even though it shows up as income on the first page,if you have capital gains or qualified dividends the tax is not taken from the tax table but is calculated separately from schedule D. The tax will be calculated on the Qualified Dividends and Capital Gain Tax Worksheet. It does not get filed with your return. See this FAQ
https://ttlc.intuit.com/community/forms/help/form-1040-line-11-amount-is-less-than-standard-irs-tax-...
In the online version you need to save your return as a pdf file and include all worksheets to see it.
