I recently sold an investment that earned a sizable (about $20K) short-term capital gain. I know that I'm going to owe income tax on this amount for the 2014 tax year, and although I don't know the exact amount I'll owe, I'd like to get it out of the way now. Is it possible to send the IRS a check now and say "please count this against my 2014 taxes." Almost like an additional withholding from my paycheck (except my current withholding on my W4 is already at 0 so I can't make it lower).
It would probably make more sense for me to simply deposit my estimate for the capital gain tax bill in a separate account and not touch it, to make sure I have enough to pay it when the time comes to file my 2014 taxes. That way I could at least earn a little interest. However I'm just wondering if it's even possible to file an estimate of taxes like this super early for the next tax year, before the current tax year is even over.
Some details: I work a salaried job, I'm single, living in a state that doesn't have state capital gains tax. Since I'm not self-employed I don't think I can just increase my quarterly taxes, so I don't see any other way of "paying early" by decreasing my withholdings for a few periods or increasing my estimated taxes.