Why am I paying capital gains on stocks when we filed jointly and made less than 75,000?

See this from the IRS

https://www.irs.gov/taxtopics/tc409#:~:text=Capital%20Gain%20Tax%20Rates,or%20qualifying%20widow(er).

@enurquezbon  said: "Couples filing jointly have an allowance of $100,000 and pay $0 on capital gains on stocks".

 $100,000 is not true.  Even the correct amount ($80,800) is often misunderstood.

Long term capital gains are taxed at 0%, if a couple's taxable income is under $80,800 (2021 threshold).  However, taxable income includes the capital gain, itself.  It's best explained by example:

Couple has $75,000 of wage & other income plus a $50,000 capital gain, for $125,000 total income.  Less the standard deduction of $25,100 = 99,900 taxable income.  99,900 – 80,800 = $19,100 of the capital gain will be taxed (at 15%). The other $30,900 of the gain will be tax free (technically taxed at 0%). 

 See:  https://www.nerdwallet.com/article/taxes/capital-gains-tax-rates