Sold stock - Do I need to remit capital gains taxes now?

you'll get a 1099 from your brokerage company at the end of the year and you the amount you owe is included in your 2014 taxes.

quote:

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I'm interested in the underpayment penalty depending on how much it is.

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In a nutshell:

You have to have paid in 1/4th of the "minimum" taxes for each payment date, which is April 15, June 15, Sept 15, and Jan 15 (Jan 15 of following year). Withholding is considered to have occured in four equal parts - one for each payment date.

The minimum is the smaller of:

1) 100 percent of your prior year tax (110 percent of your prior year tax if your AGI exceeds 150K)

2) 90 percent of the actual tax you owe for the year.