Taxes on stocks.

It all depends on a lot of things.... things like wages, witholdings and stuff like that. Its different for every situation

There is no way you get a refund and have to pay some in.

If you get a refund usually, you'll get a bigger refund.

If you usually owe taxes, you'll owe less.

The deduction is maxed at 3000$, meaning if you are in the 15% tax bracket, you get to pay 450$ less taxes.

So if you owe 500$, you'll now only owe 50$.
Remember you can only reduce taxable income to $0.

Whatever is over 3000$ you get to carry over to the next year, and however long it takes at 3000$/yr

Pretty sure you'll be filing the regular 1040 with a schedule D this year