Why did we pay tax on qualified capital gains this year? We made $83,000 adjusted gross income this year and are in the 12% tax bracket.

[MelindaS1]

The net capital gains tax rate of 0% only applies if your net long-term gains exceed your net short-term losses. This means you had to have held the assets for over a year before selling to qualify for the 0% rate. If you had net positive gains on assets that you held for less then a year, then that would be a net short-term capital gain, which is taxed at your ordinary income tax rate. 

See - IRS topic 409, section Capital gains tax rates

TurboTax, "A Guide to the Capital Gains Tax Rate: Short-term vs. Long-term Capital Gains Taxes"

Were the gains from investment asset(s) that you held long-term (over 1 year)?

[Mike9241]

you can wait until you pay your fees and then view the capital gain and qualified dividend worksheet to see how the tax was calculated, or use the worksheet in the Schedule D instructions and do the calculations by hand page 15

https://www.irs.gov/pub/irs-pdf/i1040sd.pdf